Jupiter, Moon rise north of east

Event Date: October 4th
Time: 10:30 PM


Brief

   I feel as if I have taken a hiatus from Jupiter over the last few weeks, so will come back to it for today and tomorrow's entry.
   Starting late this evening, look for the giant planet on the rise not far east of the waning, gibbous Moon.  Both are near the Hyades, with the Moon closest to the star Epsilon Tauri, making up part of the open cluster.  Since the Moon is moving about one diameter-per-hour east, being about 1/2º, it will spend the rest of the night and early morning gaining on Jupiter; getting close to it as we see both set in the western morning sky. 
   Here are both displayed low in the east-northeast, with their orbits showing as well.  I left the ecliptic out this time to avoid confusion with one too many lines.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   At the time above, the Moon (unlabeled) is about 7º away from Jupiter.  As we can see from the orbits, it will pass south of Jupiter by a small amount, not occulting it.  This will remain the case over the next few years, as the Moon's descending node (arrow to the upper right) moves a little further west each time it comes close to Jupiter.  Although Jupiter is in retrograde right now, it is moving west too slowly for us to witness an occultation.  Keep an eye on the pair however with each time the Moon gets close; once they both reach the Moon's ascending node, we can look forward to occultations again seen in different parts of the world with each encounter.  For now, enjoy them as a close "couple".  Even though the Moon is seen about 40 times the angular size of Jupiter, the planet's diameter is dozens of times that of the Moon.  Of course, with the Moon only about 239,000 miles away as a mean distance, Jupiter is over 400 million miles away from us!

Mercury, Saturn at same azimuth

Event Date: October 3rd
Time: 7:00 PM


Brief

   Let's see how Mercury is doing, as it slowly emerges south of the Sun, seen here in the west-southwest.  As mentioned a couple of weeks ago, Mercury will take awhile this time to reach greatest elongation, as it first reaches aphelion and loops further from us on the other side of the Sun.  As it passes aphelion and starts to get closer to the Sun again, it does so when it is not far past greatest elongation, and we start to see it a bigger in angular size than we do at aphelion.  Remember of course, that we start seeing the shadowed side of it and therefore, it appears to wane in phase.  Therefore, as mentioned with Venus only at 71% yesterday (albeit waxing not waning), we will not see much disc illumination at all from Mercury; hence a rapid dimming shortly after greatest elongation. 
Here is Mercury now, showed zoomed out and also in at a low magnification.  Notice for the zoom-out, that Saturn is seen just above it, yet dimmer than Merucry (-0.3 this evening).  Saturn is about +0.7, roughly twice as dim on the apparent magnitude scale.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   For image one, Saturn is a little further north than Mercury in ecliptic latitude.  Therefore, the two never get extremely close together and even if they did, get washed out by the Sun easily.  Despite Mercury being brighter, it is far enough south of the Sun right now that a non-obstructed horizon would also make viewing difficult.  Over the next few years, we we see closer pairings of Mercury and Saturn, when we see Mercury near it more similar ecliptic latitudes.
   As for the second image, Mercury is too small and low in atmospheric pollution to try to magnify too much; even with a telescope that can handle 2-300x, that isn't necessary.  As a reminder, Mercury is nearly featureless, resembling our Moon more than anything.  Of course, our Moon is so much closer than Mercury is too us, that we can see features on our satellite easily. With Mercury, it has taken the proper type of space mission with necessary protection, to get that close to a planet so close to the Sun.
The zoom-in shows Mercury at 1º, which is about 50-55x in magnification.

Moon's paths and waxing phase

Event Date: October 2nd
Time: 7:00 AM


Brief
 

   Yesterday, I showed Venus at transit, still several degrees from the Sun, as it moves towards superior conjunction early next year.  One of the better times to still view Venus however, is before Sunrise, or even the first several minutes during it, when the limiting magnitude of the sky is still low enough to see it easily.  Since we have reached the best time of the year for eastern morning geometry of the sky, Venus has maintained a good altitude at Sunrise over the last few weeks: its declination gap with the Sun has not shrunk much, as the Sun has been sinking south faster, being further east of Venus.  To further show this, here is the local and celestial paths plotted for Venus.  The ecliptic marks the Sun's celestial path, so to avoid redundancy, I left that out.  The paths for Venus cover the last two months, with the plots 5 days apart.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

  As seen above with the image, I "bent" the horizon to show more sky.  We cannot see the entire celestial path, since (1) Venus has picked up speed in prograde motion and (2) the sky has shifted slightly more than a degree every day.  As for the local path (green), we are only starting to see over the last 25 days or so of the 61, that it has started to lose a little of its declination gap with the Sun and therefore, rising a little later each day. 
As we get closer to superior conjunction, while the geometry of the eastern morning sky starts to fail quickly in January and February, the declination difference between Mars and the Sun quickly shrinks, with the Sun becoming more north by early-mid winter.
  Finally, as we look at the ecliptic, we see how it makes almost its steepest angle with the horizon at this time of year.  The Sun only about 5 minutes from officially rising, and Venus is an impressive 37º in altitude.  The Sunrise gap between the two is still 3 hours, 19 minutes this morning (Venus at 3:46 vs the Sun's 7:05) while the declination gap between the two is almost 16º.  In a few days, they will be a little closer to that 16º peak.
   This second image below shows Venus as a waxing gibbous.  The field is 1/4º, while the phase of Venus is 71% and 16 arc-seconds in angular diameter.  Since it is not completely "full", the way we see Venus near the time of superior conjunction, we only see about 11 arc-seconds of disc illuminated (about 71% of 16).  The magnification of Venus here is approximately 200x.

Sun south of equator; Venus still transiting high

Event Date: October 1st
Time: 12:58(.10) PM/10:27(.08) AM


Brief

   As we enter the final quarter of the calendar year, fall is quickly becoming more obvious, with the Sun rapidly sinking south of the celestial equator.  Between now and the last day of the month, our star will move about 11º more degrees south, after moving about that number already during September.  Before jumping ahead of ourselves that much, let's look at where the Sun is now relative to the celestial equator, at 3º south, and where the ecliptic is in relation to the celestial equator east and west of it.  The Sun is shown at transit below:

Detailed

  The Sun is still transiting above the sky's mid-latitude mark of 45º, by a few degrees at 48º, as seen from our 38º latitude.  Therefore, it is still over 11 1/2 hours of daylight, leading to mild-to-warm weather in most parts if the world at mid-northern latitudes.  The good news of course, is that the night duration is growing fast; not only because of the Sun spending more time below the horizon than above, but twilight time also a little shorter in the morning and evening.  Take advantage of this between now mid-winter, when it becomes more obvious that the days are growing longer again and we have less minutes--eventually hours--of nighttime for viewing.
   Finally, while enjoying the Sun in the daytime sky this month, we still have Venus separated from the Sun enough to view easily.  Our "twin" planet is still slightly dimming each day as it shrinks in angular size faster than waxing.  However, that is not too noticeable to us with the eyes and in the daytime, worth tracking down.  Try finding it during mid-morning hours when it is still high enough above the horizon.  The following image shows the Sun moved lower in the eastern sky a couple of hours before the first showing, and this time, Venus is shown at transit.  Tomorrow, I will elaborate more on Venus' phase and position relative to the celestial equator.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

post-full moon setting

Event Date: September 30th
Time: 7:04 AM


Brief

   While I have spent the last two entries showing the short intervals between Moon rises in the east, this next entry shows the following morning after the Moon's crest of fullness.  While (near-)full Moon rises at this time of year are on average 25-30 minutes apart, the time of them setting can sometimes be be well over an hour.  As I show the Moon below at the time of Sunrise, it is still at a good viewing altitude.  Since it continues to move north in declination for the next few days, it means that it is taking longer to set.  Also, remember that the Moon is moving east by about one diameter each hour, which also helps keep it above the horizon a little longer.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   The time between sets for the Moon this morning and yesterday's is almost exactly one hour.  If the Moon wasn't approaching descending node and instead, closer to ascending node, it would mean a setting difference of perhaps a few more minutes.  Remember also, that there are times because of the precession of the nodes and declination change, the Moon rarely changes in declination at all.  The celestial guidelines above show that the Moon is moving further north of the celestial equator, while its orbit is bringing it back towards the ecliptic slowly.  Look further east (near center), and notice that descending node is still only a few days away.  When the Moon starts to move south of the ecliptic near the time of last quarter phase, while also moving to a part of the sky where the Sun is in mid-late summer, the declination change will be minimal.

full, harvest moon

Event Date: September 29th
Time: 6:45 PM


Brief

   The full Moon isn't until 8:20 PM, as shown in image two below.  However, as we look at the upcoming image, it is similar to yesterday's, with the Moon on the rise as the Sun sets.  At this moment, the Sun is about 8 minutes from officially setting.  Once again, the celestial guidelines and the Moon's orbit show.  Since I am showing the Moon a little further east than yesterday, we also see a very slight slope of its orbit to the ecliptic, with descending node below the horizon.

Detailed
  
   Seeing a harvest Moon rise usually doesn't look any different than any other Moon rise-- unless it is at a perigee or apogee extreme; October 5th is apogee.  At only about a week away from being its furthest from us, the Moon is slightly smaller in size compared to average, at 30 arc-minutes (31 is about average).  However, the illusion of the Moon near the horizon against trees, houses, etc., makes the Moon seem larger in size; an illusion that baffles me.  As the Sun starts to sink further however, and the Moon is within atmospheric pollution, it may give it a yellow-ish color.  The contrast is usually better when viewing the Moon's maria (seas), which many see as facial features; hence, the (wo)man in the Moon.
Here is the second image of the Moon at the crest of fullness.  As mentioned yesterday with my harvest Moon reminder, this is about as high as the Moon needs to get out of atmospheric pollution to start seeming brighter; farmers finishing their harvests can be thankful of this.  Also as a reminder, sometimes the harvest Moon happens in early October, when harvest deadlines may be looming closer, faster.  The field of view for this zoom-in is 1º, giving an approximate magnification of 50x.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

harvest moon rising, just shy of full

Event Date: September 28th
Time: 6:30 PM


Brief

   We approach the harvest moon over the next several hours, as it will be the closest full moon to the September equinox.  A little less than a week ago was the equinox, and the small intervals between moon rises over the last few days, remind us why this Moon gets its name.  As a reminder, the Moon increases in declination as it becomes full this month and next.  As it does, it spends less time below the horizon and above it to provide light after Sunset.  This was--and still may be today in many parts of the world--significant for farmers to finish their harvest.  Even the few days following a full Moon have it big enough to provide enough light.  Even more importantly, the full Moon and gibbous-phase ones sandwiching it spend alot of time high in the sky, making that light a little more helpful.
   Here is the Moon already above the horizon as a 99% waxing gibbous before the Sun goes down, with its orbit, celestial equator and ecliptic showing also.

Detailed

 Although our satellite is just barely north of the celestial equator, it will slowly move further north and east against the stars.  Looking at the angle of the ecliptic with the celestial equator and horizon, that is a reminder, as well as the Moon's orbit still a few degrees north of the ecliptic.  Although the Moon approaches descending node this week, that will only partially slow down its declination "rise" north.
A few years ago, we were seeing an even more interesting scenario, in which the Moon's ascending node was closer to this part of the sky, and the time between rises was a few minutes less than now.  Moonrise is officially seconds before 6:40 PM, and tomorrow, can you predict what time it will be?  Taking our latitude into account as well as what I mentioned about the Moon's position on the celestial equator, try taking a guess.  I will show it again tomorrow very near full the crest of fullness, on the rise.

Mars' paths: celestial and local

Event Date: September 27th
Time: 7:15 AM


Brief

   Yesterday's journal ended with a tease about what I will talk about this evening with Mars.  As mentioned then, the change of separation with the Sun and improving western, evening geometry of the sky will mean that Mars will not seem to change much in altitude.  Unlike the other outer planets, Jupiter through Neptune, Mars is much closer to us and therefore, it takes longer for us to separate from it between the time of opposition and conjunction; a little over a year. With the other outer planets, it takes a little over 6 months between opposition and conjunction, depending on how far they are from us; Jupiter takes closer to 7 months, depending on how it and Earth are positioned relative to each other on the celestial dome.
   Below, is Mars shown just after Sunset, along with its celestial and local paths.  The increment dots are 10 days, covering a period of three months.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Try not to let the direction of the paths deceive you.  Instead, let's look at the spacing between the increment dots.  Although not obvious, the spacing between them for the celestial path (orange) become a little further with each one; looking closely, this may be noticeable.  This indicates what I said yesterday: as we move further from Mars, from our perspective it moves against the stars a little faster each day; specifically, every minute, although there is no way that I could visibly plot that many times!
   As for the local path (green), it shows where Mars was at the time above each day for the last three months.  It was about that time in June, that the Sun set at its latest and almost as far north as it does on the celestial dome.  As the Sun has set earlier each day, it meant that for awhile, Mars was too.  However, as the geometry of the western, evening sky improves between now and late-February, given Mars' separation from the Sun during each of those months, we will witness the aforementioned.  When I recreate this plot over a 6-month period at the end of the calendar year, you may see what I mean.  In the meantime, enjoy Mars, albeit far and dim.  As conjunction with the Sun gets close near the vernal equinox and we then lose Mars behind our star, it will not be easily visible again until late summer.

planets and Spica, looking west

Event Date: September 26th
Time: 7:14(.20) PM


Brief

   Our evening sky is host to three planets over the next week, although one of them is soon to fall  completely into the glare of the Sun very soon: Saturn (+0.7).
•A clear, unobstructed horizon is needed to find the "ringed wonder" and even so, optical aid is recommended. 
•Mars, (+1.2) which has been separating from Saturn for the last 6 weeks, is low in the west-southwest. Although dim and far away, Mars can still be a decent telescope target; especially with all the recent news over the last month or so about rover Curiosity up there, millions of miles away.  As we progress through the fall and Mars' prograde motion increases, the geometry of the evening sky will put it at a better apparition, albeit slightly.  We lose the planet to the Sun's glare by mid-late winter.
•Finally, Mercury (-0.5) continues to gradually pull away from the Sun, and still bright enough to see low in the west.  The planets are labeled below, with the star Spica near them, and more info to follow.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Although Spica is very low to the horizon, as Mercury is, I included it as a reminder about the triangle configuration that we saw change weekly with Mars and Saturn.  Now, Mars has moved far from it and Saturn, which moves slowly enough to still be about 6 1/2º away.
   Mercury's emergence from the Sun is slow, being further south of it, and setting only 30 minutes later this evening.  We will have to wait about another two weeks to see it clearly, as the Sun continues to set earlier and the declination gap starts to slowly improve between the two.  Using optical aid, try finding elusive Mercury as soon after Sunset as possible, while it is still high enough up, and a high elevation with no obstruction is highly recommended.
Mars sets a little more than two hours after the Sun, and this gap will vary during the next four months, depending on both the declination difference and separation of the two.  As hinted above, with our improving west-sky, evening geometry throughout the fall and most of winter, coupled with Mars' increasing movement in prograde motion, it will seem to stay at a similar altitude at Sunset.  Find out more about that and its path tomorrow.

analemma: 6 months worth

Event Date: September 25th
Time: 8:00 AM


Brief

Let's do an analemma update, which I last did near the time of the June solstice.  Now that we are a few days past the September equinox, we are a little over halfway through the astronomical year.  By setting a time and sticking with it every day for a little over 6 months, here are the local-path plots, incremented by 10 days.  The first plot starts on March 19th, being the March equinox and the last being today's date.  The second image is a zoom-in of the same path for the same time duration, showing the plots closer to the summer solstice more defined, being much closer together than those closer to the equinoxes.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   As a reminder, the separation between the plots change with the declination of the Sun.  As the declination rate of change slowed down near the June solstice, it didn't change at all at the second of the solstice.  If I were to change the plot-increment from every 10 days to every day, this would be more noticeable; I refrained from that however, because to magnify the analemma to see all of them at/near the time of the solstice, I wouldn't beable to fit the entire path in the image.  Therefore, try to image it, and remember how many times I have shown the ecliptic and celestial equator together in past images if you are not convinced!  The declination rate changes fastest at the time of the equinoxes, as we notice for where the Sun is; those plots are much further apart.  Whereas near the solstice, the declination change is about 1 degree over a span of about 10 days, it changes by 3 or 4 degrees during that span very near the equinoxes.

Jupiter transits high, and higher!

Event Date: September 24th
Time: 5:54 AM/5:34 CDT*


Brief

   Jupiter is still about a year away from its best declination.  However, while in Taurus, it is still very high in the sky at transit, a little more than 21º north of the celestial equator; 74º at transit, as seen from our latitude, and at/near zenith as seen from Mexico, Hawaii, the Caribbean, and some other island countries at/near the 21º latitude mark.  At those locations, Jupiter doesn't spend quite as much time above the horizon each day as it does at our mid-northern latitude.  The first image shows the planet at transit from our location.  Both the altitude and celestial grids are shown. 

       

Detailed

As I have shown several times, the more north we go on our globe, the longer a northern hemisphere planet or star is visible, declination pending as well.  Now that days at the north pole have the Sun below the horizon for about the next 6 months, and other latitudes north of the arctic circle are experiencing twilight skies, anyone braving those super-cold conditions have Jupiter low to the horizon all hours of the day.  Since 90º minus 21º equals 69, and the arctic circle's latitude is about 66.5º, that only gives a few degrees that Jupiter is not above the horizon.  At latitudes closer to our equator however, we see less of Jupiter as a result of less dark hours in comparison to seeing the planet from the arctic circle.  However, it is seen getting much higher in the sky. 
   For the second image*, I searched for a location very close in latitude to the declination of Jupiter, so we could see a transit extremely close to zenith.  That location is Aguascalientes (hot water?), Mexico, and the altitude at transit is 89º 58.3' for Jupiter.  At 21º 53' in latitude, this puts the viewing location at 1' 41" north of the latitude where Jupiter would be seen at zenith, which would be a little over 100 miles south.  Both grids show again, and by using the altitude one, we can see that Jupiter is nearly in the center of the circle which traces out an altitude near zenith.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Mercury and Saturn become less separated

Event Date: September 23rd
Time: 7:15 PM


Brief

   As we enter autumn for the northern hemisphere, we have two planets following the setting Sun.  One is too much in the glare to see, despite being somewhat-bright in apparent magnitude: Mercury (-0.7).  Further out of the glare, Saturn (+0.7) sets a little over an hour after the Sun.  As Mercury separates itself from our star further while Saturn moves towards conjunction, the two will become closer together.  However, with Mercury sinking below the ecliptic and Saturn a couple of degrees north of it, they never come impressively, close together. By the time they will be at their closest, Saturn will become a little harder to see, getting closer to the Sun.
   Here is the showing of them this evening, at 16.5º apart.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

  Although Mercury's orbit makes it seem as if it will stay close to the ecliptic for the next week or so, that is only based on our view now.  As we revolve around the Sun at our own rate, our perspective of Mercury's orbital plane gradually changes.  This is the same reason that we only see it transit the Sun in May and November, when the timing is right.  It isn't Mercury's orbit that is swaying up and down; it is the inclination of our orbit relative to its.  With the inner planets revolving around the Sun more often than Earth, it means that if we could see the orbits, we would notice some up-and-down.  Right now, since the thicker (closer) part of the orbit is lower than the thinner (further) portion, it means that we are not only looking at Mercury's plane at a sharp angle; we are also viewing it from a latitude far from the planet's equator.  This last part doesn't matter for Mercury, yet it can for planets such as Saturn, which has us see its rings edge-on about every 15 years, and see the rings as if we were almost viewing it pole-down, about 7 years + a few months before and/or after every edge-on year.
  

September equinox

Event Date: September 22nd
Time: 7:43(.11) AM


Brief

   Happy September equinox!  For northern hemisphere viewers, we can also say "happy autumn".  It is hard to believe that this much time has passed already since my first blog-entry of my journals, featuring the March equinox.  As a result of my excess text and images there, I will keep this one much shorter. 
    As the case with the March equinox, the September one features the Sun crossing the celestial meridian and ecliptic at almost the same time...but not quite; the detailed section tells those following the images below of the zoom-out and zoom-in of the Sun and lines.  Also, as the time shows above, it crosses the ecliptic meridian at a slightly different time.

Detailed

   As I mentioned when talking about the March equinox back then, there are very few times over centuries-worth of years, that the Sun will cross the ecliptic, ecliptic meridian, and/or celestial meridian at the same time; crossing all three at the same time is beyond extremely rare, yet the spacing in between such times is very small so it isn't worth getting concerned over when calculating the equinox.  For this one, the time that it crosses the celestial meridian is 7:37(.30), and the time that it crosses the celestial equator is 7:35(.03) PM.  Once again, these differences can vary with each equinox from year to year.  When looking at the zoom-in for image two above, if we imagine precisely where the Sun's center is, the intersection of all three are close.  An even further zoom-in below, taking the Sun away, still has the image centered at the Sun's center, and we can see that all three--the meridians and celestial equator--don't all meet at one point.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

 

another bear-symbol in the sky??

Event Date: September 21st
Time: 8:34(.22) PM


Brief
   There is a spectacular double star in Cygnus--within Summer Triangle boundaries--which I have failed to acknowledge all summer long--shame on me!  It is Albireo, which to people who live in the San Francisco Bay Area--if not beyond--is also called the "Cal" star(s): one blue, one yellow, er...gold*.  How deep a yellow color may depend on how powerful one's telescope is, and/or whether or not a person is looking at the pair during a stage of twilight or complete darkness.  Nonetheless, when a viewer points to Albiereo, it is a sight not to be forgotten.  Granted many, or to certain people, most stars are boring to look at in comparison to planets, clusters, nebulae and the closer galaxies.  To prove otherwise with Albireo, here is a zoom in at transit time, preceded by a zoom-out to show its position relative to the other Summer Triangle stars: Vega, Altair and Deneb.
The zoom-in is about 270x magnified to show them separated, yet in even the small telescopes at 1/3rd of this magnification, the color and separation is easy to detect.  Of course with the eye, they appear as one, and color is difficult to detect on even the clearest of nights.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

Although I didn't include the meridian in image one, which would obstruct Albireo almost completely, its transit time can remind us of something I talked about earlier this year a few times: the transit time of the Triangle's "center".  This evening, that time is about 8:45, or 11 minutes after Albireo's transit time.  That isn't too important to remember, unless you are a transit-comparison nerd the way I am sometimes! :-P
   As for some characteristics worth knowing about Albireo, the stars are two different magnitudes: 3 for the gold, 5 for the blue (dwarf).  At only 35 arc-seconds apart, that is why they are too difficult to see apart from each other with the eye alone, which can perhaps only detect 1 or 2 arc-minutes apart at best for some doubles in the clearest darkest of skies.  However, they are about 7 light years apart, meaning that if a binary system, they could take close to 100,000 years to revolve around each other.  Even closer together, are the gold with a companion of its own.  This star creates a spectrum, which proved its existence; that is good, since telescopes on Earth would have to be powerful enough to split the star, and such are not easily portable . 
   As we enter our last hours before the September equinox, enjoy this "jewel" of a double, with the blue and gold together and, oh yeah...go bears!**

*University of California Berkeley
**UCB's team

deep sky markings near the Lions, Big Bear

Event Date: September 20th
Time: 5:30 AM


Brief

   Yesterday I showed Leo Minor zoomed in with some stars labeled along with those of the small stick-figure, which doesn't seem to represent a lion at all-- compared to the big Lion constellation anyway.  Also, this is a part of the sky where we are looking close to perpendicular out of our Milky Way, so the density of stars per arc-second of sky is smaller.  However, we can still try to find some very deep sky objects in this area: mainly galaxies, yet also a couple of nebulae nearer to the Big Bear.  Zooming out, I labeled a few of these shown below, near the constellations that I talked about in yesterday's entry.  As seen, there are many others in the east-northeast at this time of day and year as well, while still dark enough.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Many of these, including a bright one near the Big Bear's tail (Dipper's handle), are emission or planetary nebulae.  The emission nebulae, as viewed with small telescopes mainly have a grey appearance.  Other times, as seen with a more powerful telescope, a red appearance, as hydrogen gas becomes heated by young stars which are very hot already.  When the gas becomes heated to about 10,000 kelvin, the red (or some other colors for certain nebulae such as the Orion) starts to show.  As for the planetary nebulae, they are seen for only a short time compared to the emission ones: the gas shell becomes fainter as it grows out further from the central (dying) star, blending in with surrounding interstellar medium.  The time it takes for this to happen is about 10,000 years.  Tomorrow, I will show one of the most popular planetary nebulae in our sky, which can be seen easily in a dark sky with even portable telescopes.  Do you have any idea which this is?  Hint: it is barely within the boundaries of the Summer Triangle, made up of Vega, Deneb and Altair.

the small carnivor-- between two big ones!

Event Date: September 19th
Time: 6:00 AM


Brief

    For many months, I would show the Big Dipper marking the Big Bear [Ursa Major]'s lower body and stretched-out tail.  However, I failed to ever show the entire bear, including head, leg, feet and upper body outline.  The stars that make up this part of the constellation--being most of it--are in the 3rd magnitude range, being only easily bright without light pollution.  Most places where people view the Dipper, are closer to urban or suburban settings, with streetlights on or maybe some other obstruction.  From an area where there is no light, such as a campsite up in the mountains, the stars are much more visible, although the stars of the Dipper may already seem bright enough to still grab much more attention.
   Here is the Big Dipper seen on the left side of the image (north) getting higher in the sky each morning before, with a much more abstract, smaller constellation between it and Leo: Leo Minor, the little lion, has a stick figure made up of two 4th magnitude stars and one 5th magnitude one.  Is it any surprise that most people don't think much of this constellation?  Well, they should, for one big reason; more about that in the detailed section!

Detailed

  Each November, the Leonid Meteor Shower is visible, starting sometimes before midnight, yet peaking during the wee hours of the morning when the Lion's radiant is above the horizon.  The radiant of the namesake constellation for most of the meteor showers is normally within a constellation's boundaries, yet sometimes near the boundary of it and another.  If you remember the Perseids in August, we started seeing the radiant a little early before Perseus was high enough above the horizon; it was closer to Casseopeia.  As for the Leonids, which are a result of our Earth passing through debris of the comet Tempel-Tuttle, the radiant is a little closer to the more recognizable stars of Leo. Some years, the shower is better than others and of course, hope for a Moon that is less than half full to avoid that type of light pollution.
   Now, what does this have to do with Leo Minor??  Simple.  The little lion's figure is close enough to the radiant, that if you try to view this small constellation through binoculars (try a wide field of 10º), there will be several meteors passing in front of it!  As we see the meteor shower when the Lions are the altitude shown, those looking as if they are moving to the upper left (northwest) of the radiant, are passing by--or through-- Leo Minor.  It is almost as if the Big Lion is being a bully and pelting his "cub" with small, fire-glowing "rocks"!
   Use this second image below to magnify on the dim Leo Minor, with its few bright-enough stars to create a stick-figure, and others still barely visible before being washed out from the Sun; they are about as bright as those that make up the stick figure.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

More on the Sickle of Leo: stars

Event Date: September 18th
Time: 6:00 AM


Brief

   Yesterday, I showed Regulus, the brightest star of Leo the Lion.  However, can you spot the asterism that it is part of before the Sun washes it out?  The Sickle, which I showed last spring and perhaps once during early Summer, looks like a backwards question mark, with Regulus marking the dot "." at the bottom.  We don't see the rest of the Lion yet--body and tail--with the Sun in the way of that eastern part of the constellation.  In about a month, we will see the Lion in its entirety, as the Sun moves further east-southeast on the celestial dome.  Here is Regulus labeled, with the stick-figure of Sickle, being the Lion's mane.

Detailed

   The Sickle is made up of five moderately-bright stars along with 1st-magnitude Regulus.  Algieba, labeled below, is slightly brighter than some of the others.  Below, I labeled each one.  While Algieba-- a fine double star--is magnitude 2.0, the others are in the high-2 to high 3 range of magnitude.  Regulus in comparison, is magnitude 1.3.  By forming the head--or mane--of The Lion, it makes it one of the most distinguishable asterisms in the sky after the two dippers.  When we see the entire Lion body in a few weeks, the mane-shape may make much more sense.  Try to visualize it, since any stars designated as the face of the lion are much to faint to make it out easily.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Venus slowly approaching Regulus

Event Date: September 17th
Time: 6:00 AM


Brief

    As we approach the September equinox, we see Venus rising about 3 1/2 hours before the Sun, as seen from our latitude, followed by Regulus.  The star is not only west of the Sun now; it is becoming further north each day.  Since the Sun is rising about 1 1/2 minutes later each day while Regulus is rising a little less than 4 minutes earlier, it means that we will see Regulus for more than 5 minutes more each day before Sunrise during much of the autumn season. 
Here is Regulus about an hour before Sunrise, already 13º above the horizon.  Notice how it is very close to the ecliptic, less than 1/2º apart.

Detailed

   By showing the celestial equator in the image as well as the ecliptic, the two merging below the horizon at this hour indicates how quickly the Sun is moving towards the equator and south of it at this time of year.  Look also at Venus, which is a hair over 18º separated from Regulus.  Since Venus is gradually speeding up in pro-grade motion, as I have mentioned several times over the last month or so, it will catch up with Regulus.  While sometimes we view Venus with a large value of ecliptic latitude, this will be a time when we view it with a small one--almost that of Regulus' at the time that it catches up with the star.  We will see a fine pairing of the two early next month.  By remembering that Venus is moving further east each day, we can try to predict exactly which morning it will happen.  Using its celestial plot in the image below zoomed in a bit, can you?  Once again, as the celestial path of Venus shows, it is a very slow increase, yet still enough of one.  Between now and tomorrow at this time for example, the planet moves about 4.5m in right ascension, and 14.6' in declination.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Mercury emerging east of the Sun--low

Event Date: September 16th
Time: 7:20 PM


Brief

    The upcoming apparition for Mercury will be interesting, as there are a few pro's as well as a couple of cons.  Normally, as the ecliptic's angle with the horizon shows in the image below, this is one of the worst times to view Mercury in the western evening skies during this time of year.  Of course, as Mercury swings in orbit between superior and inferior conjunctions, it also dims a little each evening. further hindering viewing.
   Before I get to the pro's in the detailed section, let us check out the planet slowly emerging from the Sun, its orbit, celestial equator and the ecliptic.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

Mercury is approaching aphelion over the next three weeks, meaning that we will see a slightly larger separation than we sometimes do, near the time of greatest elongation.  At over 23º, this is short of the 28º separation that we sometimes see when greatest elongation happens during an August evening or April morning.  However, it is still enough to make Mercury a little more visible as the Sun continues to set over a minute earlier each evening for the next few weeks.  Greatest elongation will not happen for over a month, as seen from our perspective and Mercury being further from the Sun during aphelion.  Around the time of greatest elongation, Mercury will start to get closer to the Sun again.  As a result of this change, coupled with Mercury coming closer to us a little each week in its orbit, its rate of dimming becomes very slow in late October.  When it finally reaches greatest elongation, it will still be a good magnitude of -0.1.  By then, the geometry of the western evening sky also starts to very slowly improve, as the declination of Mercury becomes less-south of the Sun.  Unfortunately for the elusive planet, it shortly gets back into the glare of the Sun shortly after that, dimming quickly as we see it wane. 
Long story short, to see Mercury well again, look forward to its next morning apparition later in the season.  In a few weeks, I will revisit Mercury as the geometry gets better and it separates itself more from the Sun.

Venus near crab-star

Event Date: September 15th
Time: 5:30 AM


Brief

Earlier this season, I showed Mercury near the star (A)sellus (A)ustralius, (Delta Cancri), magnitude 3.9.  Yesterday and this morning, we have Venus with about as close an encounter with the star as Mercury had: 1.3º for Venus and AA.  The biggest difference between now and then, is that Venus is so much brighter than Mercury, so it is not as easy for the star to stand out when looking without optical aid.  Venus overwhelms it, while smaller, further Mercury looked much dimmer to us and closer to that of AA's magnitude.
Below is a zoom-out of the two, followed by a 2º zoom-in.  Since several days have passed, AA rises alot earlier than it did during its conjunction with Mercury, while the sky continues to increase in darkness by over a minute each morning.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Venus will move away from AA quickly over the next few days, and fall out of this field.  The two will remain visible together in binoculars for a few more days, before Venus separates itself too much.  With the eye alone, it is a little better to see them just before or after their closest encounter; Venus' brightness won't get in the way of AA as much.  Keep in mind also that when Venus has a close encounter with the same star for each revolution [around the Sun], the separation can greatly vary; it depends how we view Venus in orbit against the stars from our position against them, on Earth.  The next time that we see them at their closest will be during evening of July 4th of next year, slightly further separated.  Besides AA, try viewing Venus near other stars when close--particularly brighter ones so easier to see with the eyes near Venus) and monitor each time that Venus comes back to that star,  As we saw with Venus and the Hyades star cluster earlier this year, it passed that in retrograde and prograde, so the double-pass of a star can happen within the span of just a couple days if close enough to retrograde  during that 48-hour period.  If Venus is very near the star, during the day of its retrograde to prograde motion for example, it can spend a few extra days near it.

Pluto's start field: not much change nightly!

Event Date: September 14th/October 4th* (see after image 1)
Time: 9:00 PM


Brief

   We know that Pluto can be challenging to find as a result of being a magnitude as dim as the dimmest stars through most amateur telescopes.  However, just for the sake of curiosity, have you ever observed its field?  Since Pluto moves very slowly, at a rate slightly less of 1.5º each year against the stars (360º/248 years), we can successfully use a field about one-sixth that size (1/4º) to try to track it.  Under the darkest of skies, this size field being of magnitude somewhere between, 260-270x, is just enough to see Pluto as a dim "star".  Although only looking a tiny amount of space, let's label a few stars so to see how slowly Pluto is actually moving.  Since it is now picking up speed very gradually in prograde, being long past its opposition, it is a good test.
   The first image shows Pluto centered, with a star at the edge of the field labeled.  Since this marks the radius of the field, the two are 1/8º (about 7 or 8 arc-minutes) apart.  The star that I picked is just slightly brighter than Pluto.

The second image shows us jumping ahead by 20 evenings*.  Notice how the star has moved by about the 7 arc-minutes since then.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Image two's celestial path of Pluto shows two things: it quickly picks up speed in prograde motion during the last 10 days; the inclination of Pluto's orbit has it curve towards the star rather than go more in a direct line.  Since Pluto's orbit inclination is 17º, with a slope almost always changing against the ecliptic, we see this unusual curve shape that we would hardly see with any of the "classical" outer planets: Mars through Neptune.  Also, during the 20-day span shown, the star moved only about halfway across, if keeping Pluto centered,  Therefore, if we say that Pluto moved about 8 arc-minutes over almost 3 weeks, that it moved a little under 3 arc-minutes a week.  Regardless of number accuracy, this brings me to the point of getting familiar with Pluto's field: if you study and get to know it well one night, you will see almost the identical field with it centered a week later, using the same eyepiece.  Granted, we get the Moon in the way for that part of the sky every month for a week or so.  Therefore, try this exercise during weeks when the Moon is crescent or new, as is the case this week as a waning crescent; it will not rise until hours after Pluto gets too low and eventually sets.

Uranus within Cetus: other nearby constellations

Event Date: September 13th
Time: 10:00 PM


Brief

   Yesterday I showed Uranus, rising in the dim-east sky: a part of the sky filled with some dim constellations with very few stars easy to see if there is a Moon or light pollution.  Fortunately, the Moon is already set as a waning crescent, while light pollution may not be an issue if we view at a high elevation.  With that said, the image below shows the constellations close to Uranus.  As mentioned before, it is at the Pisces-Cetus border, just within the sea-monster's boundary.  Two more slightly brighter constellations are north of Uranus and Pisces: Pegasus, including its "great-square" asterism, along with V-shaped Andromeda.  Stick figures are included for each of the four.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

Since we are looking perpendicular out of our galactic plane, we are not looking at much celestial matter close to us.  As a result, although there are several billion stars in the direction of these constellations, we usually look into more dense areas of stars when we are looking either towards the direction of our galactic center, or the outer arms; Auriga, Taurus, Gemini, as examples of constellations in the latter direction, opposite the center.  We will see these mentioned constellations rising later in the night, while they are evening risers during the late fall and early winter.  As a result of looking perpendicular for now in the direction of Pegasus and Andromeda, it means that we have a major attraction to look at shortly before seeing the constellation's figure rise.  I will remind of that tomorrow, and as a hint, have a very dark sky to see it's entire shape.

Uranus nearing opposition, and a "fish" star

Event Date: September 12th
Time: 10:00 PM


Brief

   Uranus is nearing opposition: rising in Cetus near the Pisces border during mid-evening twilight and placed high enough to search for shortly before the listed time here.  Remember to wait until it gets high enough out of atmospheric pollution if you want to see the bluish-green color which makes the planet unique.  Similar to Neptune further out, Uranus is made up of methane and ammonia gases.  With a strong enough telescope, Uranus' disc shape can be observed, as opposed to looking like just a non-twinkling star.  Try magnifying around 200x minimum, as the disc size is less than 4 arc-seconds.  First, I will show the position relative to the horizon, in the east-southeast

Detailed

   As we get closer to opposition, we see Uranus for about 4 more minutes in the sky each night.  By the time opposition happens, the Sun and Uranus will be close in declination, with the Sun a little closer to the celestial equator.  Uranus is about 2.2º north while the Sun is quickly moving to the celestial equator, for the September equinox.  I bring this up, because it is a rare time that we have an opposition this close to an equinox; it was a little closer last year when Uranus was also a little closer to the celestial meridian; just past where the Sun is at the vernal equinox in late March.
   This second image shows Uranus with a 1º field.  I have done this before, yet because of retrograde motion, the star field of Uranus has changed since a month ago.  Also, keep an eye on star 44 Piscium (mag 5.8) that Uranus passed by during prograde earlier this year, and will pass again early next year.  Not only is it the brightest star in this field,  Uranus and it have a very close encounter coming up.  Watch them carefully each evening when viewing, and try to predict which day they will be closest...and how close!

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

  

Winter Circle stars "sparkle" dark sky

Event Date: September 11th
Time: 10:00 PM


Brief

When we get into the fall months, particularly the later weeks, the Winter Circle dominates the eastern sky as a large asterism made up of many 1st magnitude stars--or brighter!  As the case with all stars, the circle's rise four minutes earlier each day.  Of course, when daylight savings ends in early November, it becomes according to our clocks, just under 64 minutes earlier for that one evening.  This means with the earlier Sunset, which is already happening quickly, we will see these stars for a much longer time in the sky.
    Seen below, we see the stars in the east, as well as the trio of solar system bodies featured yesterday: Jupiter, Venus and finally, the Moon nearing on Venus separation-wise.  The celestial equator and grid are shown to show the declination differences for the planets and stars.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   In the past, we have looked at the circle, planets, Moon all grid-free.  Now, not only do the planets and Moon add to the bright "open cluster" of stars (yes, very open by appearance, being an asterism!), we can see from their declinations how long we may see them in the sky.  Capella is the most northern of the bunch, with Castor and Pollux to follow; Castor being a little more so.  Sirius is the most southern of the bunch.  As seen from mid-northern latitudes, Sirius is also the last to rise, yet among the first to set.  The other labeled stars above, along with the planets, are in between declination-wise.  Use the lines to compare, and from our 38ºN location, what does it tell you about which ones rise first?  Last?  The same for setting, as the gridlines' visibility above the horizon tells us something.  Although not shown, the gridline just north of Capella shown here, being 50º, has stars at that declination nearly circumpolar.

Jupiter, Venus and Sirius still as triangle, Moon

Event Date: September 10th
Time: 6:00 AM


Brief

For over a month, I have talked about the Venus/Jupiter/Sirius (V/J/S) "triangle" in the east, rising before Sunrise.  Now, as Venus continues to quickly move west to east, the celestial bodies has passed their isosceles configuration, and the triangle shape is starting to appear more stretched out.  Since Jupiter moves much more slowly and will start its retrograde next month, the means a faster separation between it and Venus.  Here are the three below, with a waning crescent Moon almost in line between the two planets.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

As Venus speeds up and Jupiter slows down, Sirius of course remains fixed, disregarding proper motion.  Eventually as the year finishes, we will see more of an arc-shape than a triangle.  Therefore, enjoy the shape while it lasts, and don't forget that we still have the Vega/Deneb/Altair (V/D/A) triangle of stars setting in the west at the time that these three eastern ones come up. 
   As for the Moon, we saw it near Jupiter earlier in the week, and it will pass by Venus for a fine pairing on the morning of the 12th.  Although they will be a few degrees separated, both will be easily visible for a few hours before Sunrise.  As a waning crescent, the Moon will be helped by the excellent geometry of the eastern morning sky to be visible along with Venus.  Both bodies are still far enough north of the Sun, along with their separations from our star.

waxing, "shrinking" Venus well placed at Sunrise

Event Date: September 9th
Time: 10:00 PM


Brief

   The rise-gap between Venus and the Sun is slowly starting to shrink, now that our planet is past greatest elongation.  As Venus starts to gradually approach superior conjunction, it is also waxing and shrinking in angular size, as seen from Earth.  Venus continues to move further from us each day, after being closest to us during inferior conjunction.  Take a look below at Venus with its orbit, along with the ecliptic featured, shortly before Sunrise.  The ecliptic makes a big angle with the horizon right now and that is still gradually improving between now and early October. 

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

As the separation between the Sun and Venus decreases, the geometry of the eastern morning sky continues to improve for about another month.  Therefore, Venus doesn't seem to change in altitude at the official time of Sunrise each morning.  Venus is further north of the Sun and currently, 44º separated from our star.  As we get to the later weeks of fall, Venus' closing in of the Sun means that it will lose northern declination quickly and be nearly the same as that of the Sun by early winter.  We will not beable to see Venus high above the horizon for much of winter, and will gradually lose it to the Sun's glare in March.  At that time, the geometry of the eastern, morning sky is nearly its worst.
   Venus also varies in ecliptic latitude each month, passing ascending node next season.  Remember to try to view Venus for awhile after Sunrise, since it is bright enough to stand out against the gradual-lightening morning sky.  As the weeks pass and the Sun rises later each morning by a minute and a half at best, it gives us more time to have the sky darker and easier to see Venus for several more minutes after Sunrise.

Moon and Jupiter 1 degree apart

Event Date: September 8th
Time: 3:14 PM


Brief

This morning, we witness a fine encounter of Jupiter and the Moon.  With a combination of Jupiter moving it its orbit and the Moon being affected by precession of the nodes, the two do not peak as closely as they have over the last two months.  During the first two passes of Jupiter this summer, their orbits led to near-occultations seen in other parts of the country and world; while the two were both below the horizon and/or not dark enough to easily see Jupiter from here,  we missed those.  This time, despite being a little further separated, we get to see the Moon approach and pass Jupiter while both are both easily visible.  It is still a fine sight, as these two images show.  The first is the zoom-out, and the second a 2º field showing both (about 25x magnification).  We can even see Jupiter's Moons barely visible at low magnifications, while the Moon's terminus moves fast during this phase of nearly 3rd (last quarter).

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

If a line is drawn from the center of the Moon to Jupiter, it would extend slightly over 1 degree.  The time shown at the top and the images is precisely when the Moon is closest in separation to Jupiter this time.  Since Jupiter's orbit is slightly inclined by a couple degrees with the ecliptic, and the Moon's is very much inclined in comparison by 5 1/2º, it means that the Moon will pass Jupiter a little further south each month to follow.  As the Moon passes the stars of Taurus, it is a little further south each time, and this will continue for another few years.  It will have near-occultations with Jupiter again in the upcoming years, yet it will mean that the Jupiter will have to be closer to the Moon's ascending node, currently several degrees away from it.  By the time Jupiter gets closer to the node with its own revolution movement against the stars, the node will move--via precession--towards it as well.