Hercules star cluster, and star-hopping to it

Event Date: February 4th

Time: 5:00 AM

Brief

  I have not looked at too many star clusters for this blog since starting it.  However for globulars ones, we are reaching a time of year for which two of them are seen in morning skies.  I will show what is perhaps the most popular one through a telescope this morning, and another one tomorrow.  M-13, known as the Hercules cluster (in the namesake constellation) is spectacular in large, powerful telescopes, yet can also be enjoyed in small, 6 or even 4" amateur 'scopes.  The cluster is found within the asterism keystone, which outlines the torso of the strongman.  In in the image below, is the cluster magnified a little less than 100x.

Detailed

   In the second image that I will show, I included his constellation and emphasized in bold lines, the keystone.  Also, I labeled the stars Vega, Deneb and Gienah; that's right, not Altair for now, as the 3rd summer triangle star (more on that in a couple of days).  The latter may not be familiar to you, yet look at where it is in relation to Deneb: part of Cygnus the swan's wingspan!  Despite this, Gienah's position in relation to Deneb doesn't really matter; its position to Vega does however.  If we imagine a line connecting Gienah and Vega and continue just as straight eastbound (in celestial longitude or simply upward), that line would directly hit the Hercules cluster.  Therefore, if you see both stars up, this is the way to find it.  See below:

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

  Finally, I will mention that the cluster can even be found when it is about to set and the stars are high in western half of the sky: the orientation of the swan's shape may change somewhat, but the stars are still positioned the same relative to each other!

Mercury "closes in" on Mars

Event Date: February 3rd

Time: 6:00 PM

Brief

   A few days ago, I mentioned the Mercury/Mars encounter, which is soon to happen.  Although these planets are about 98.3 million miles apart right now (not much more than us from the Sun at aphelion), they are seen as binocular friendly, in atmospheric pollution; a little more than 4º separated.  Don't expect to see any features on Mars, which we have separated to 214 million miles from; about 3 times further than it's average opposition distance.  Mercury, although much brighter than Mars in apparent magnitude, is featureless as seen from even powerful telescopes from Earth.  We can enjoy it catching up with Mars, moving west to east against the stars, shown below

.

Detailed

  For Mercury, on the apparent magnitude scale, it is a little more than 8 times brighter than Mars, with apparent magnitudes -1.10 compared to +1.17 respectively, based on the magnitude logarithmic calculation.  Since the magnitude difference of the two are 2.27, when added together, using the logarithmic formula for 100, this precisely calculates to the aforementioned 8.  Anyway, I just thought to throw that in there!

As for the separation of the two, try viewing them through medium power binoculars, of about 7º in field.  The second image shows them this way, low in the sky, a bit south of west.

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

As the next week passes, the view of the two changes from binocular friendly to telescope small-field friendly!  Can you guess yet how close they will pass at conjunction, even though I left the orbits out of the first image?  If you can follow Mercury's direction in the sky as it separates from the Sun, that can be a way to guess, since Mars is moving gradually towards the Sun, and shrinking slowly in separation.

  

midnight, with a rising waning, gibbous Moon

Event Date: February 2nd

Time: 12:00 AM

Brief

About two weeks ago, I showed the first-quarter Moon high in the sky, far north of the Sun.  Now, as the Moon wanes to last (3rd) quarter, it has moved much further south of where it was near full, about a week ago.  It is not as far south as the Sun is now, yet with every rise since turning full, the gaps have been--on average--slightly over an hour apart.  This is much different than Moonrises of the waning gibbous Moon 5-6 months ago, when I emphasized how it rose about half an hour later each evening.  Why the difference??  Simple: then it was moving north quickly, and this time, south!  Look at the image below, at where it is in the sky: about where the Sun is in late October.

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

Detailed

   When looking above, we see how the ecliptic's angle with the horizon is large.  Therefore, it means that west of the Moon along its orbit, were declinations more north than it is seen here.  The further south it moves, the longer we have to wait for it to rise, compared to the day/night before.  However this time, as a bit of a "twist", the Moon's orbit is bringing it closer to ascending node and therefore, the rise-gaps have remained about the same over the last 6 dates; only increasing slightly.  As the Moon continues to wane after 3rd quarter, the combination of the the ecliptic becoming more "parallel" with the equator (at least seen that way with the software or if imagined from Earth-viewing), the gaps between rises will shrink rapidly.  Also, the orbit of the Moon bringing it north of the ecliptic will contribute to this.  The last few days before new Moon, we will see the old, waning crescent rising at gaps very similar to full and waning gibbous Moons in the late summer/early fall.  Think six months ahead, or six months back, when comparing Moon-rise times for phases about half a cycle opposite each other.

Jupiter resumes pro-grade motion, seen high

Event Date: February 1st

Time: 7:37(.03) PM

Brief

   I mentioned a few days ago that Jupiter was approaching stationary status, after about four months seen--from Earth--in retrograde motion.  Now, having switched back to pro-grade very early yesterday, local time, Jupiter will spend most of the rest of the year passing through Taurus and western Gemini.  As it does, it first leaves the Hyades and Pleiades star clusters, passes the horn-stars of the bull, and will start to approach Castor and Pollux, the twin stars.  This, before reaching stationary once again to begin its next retrograde.

   Before getting too far ahead of ourselves, given that the planet is still moving west to east very slowly right now, let's look at Jupiter where it is now in the sky at transit.  The Pleiades is not far away in separation, and neither is the Hyades.  The second image is a zoom-in, showing Jupiter's celestial path over the last year that it has moved back and forth against the stars of Taurus: Prograde, retrograde, two stationary "stops", and now, prograde again.

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

Detailed

  At an altitude just under 73º, as a result of declination 20.8º N, Jupiter is about to reach its highest and northern points in the sky respectively, during this upcoming pro-grade.  Simply, look at the celestial grid in image two, and Jupiter's path in respect to the nearest gridlines: the planet started going north quickly, started to slowly level off, then went in retrograde at nearly the same declination as it did for pro-grade...only in the opposite direction!  Depending on the angle we view the a planet in retrograde, sometimes we see no change, while other times we may see a "loop" or high-frequency "wave" type of shape.  In the case of the latter two, it means that the planet of topic may pass the same stars at different separations: occulting one in one direction, and passing it by several arc-seconds, the next.  When viewing planets in retrograde, as we will with Saturn a little later this year when it approaches its opposition, try to keep track of unaided-eye stars that it passes in prograde, as well as retrograde; the same with Mars early next year before its next opposition.  What will you notice?

Venus nears conjunction, low in southeast

Event Date: January 31st

Time: 7:00 AM

Brief

   Venus only rises 41 minutes before the Sun this morning, and that gap is shrinking fast now.  Although Venus is moving a little faster north than the Sun, our star is still moving fast enough to stay ahead of Venus and therefore, the poor apparition of the planet as seen below.  Also, as Venus approaches superior conjunction, it gets closer to disappearing out of our view.  The Sun's glare will get in the way, and we will lose Venus from east visibility until about late-spring, in the evening sky.  Taking a look at the image, as I included Venus' orbit showing that it is losing ecliptic latitude slowly.

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

Detailed

   Back when we saw Venus at greatest elongation, it was close to its best apparition of the year in the eastern sky, and more than 30º above the horizon.  The gap between rises for Venus and the Sun then was well over 3 hours, while as mentioned, the gap has shrunk substantially since.  Even when we get Venus back in the evening sky, it will be a gradual emergence, and not seen for very long with the eye alone after Sunset for the first few months.  The Sun of course gives off lots of glare, making it hard to see a planet even as bright as Venus.  Until that time, try to still get a view of it as a tiny, 97% waxing gibbous only 10 arc-seconds in angular size.  In comparison, when Venus is at inferior conjunction, thinking back to last June, it is about 6 times closer to us, at 1 arc-minute in angular size.  When we have Venus at inferior conjunction when it is at aphelion and we are near perihelion (this time of year), Venus even is slightly larger in angular size.  This time, at superior conjunction (March 28th 10:07 AM PDT), Venus will be about a month past aphelion as we start to move away from the Sun oursleves, on Earth.  Therefore, its angular size will be a little smaller than it is now, although not optical-aid noticeable.

  

Moon near celestial equator: Mintaka comparison

Event Date: January 30th

Time: 12:43(.43) AM

Brief

   As we turn the calendar into a new day, a little more than six hours from my last entry, I will turn attention the the waning, gibbous Moon, which starts its time in the eastern sky, north of the celestial equator.  Later into the night, it crosses descending node and is seen a bit south of the equator.  

Now, you may be asking yourself, why does he bring this up??

Last week in this entry, I emphasized that the star Mintaka was the closest to the celestial equator, among stars easy to see with the eye.  I also mentioned that as a result, the star nearly traces out the celestial equator as we watch it rise almost directly east, and see it set directly west.  Seen below is the Moon rising, its orbit, celestial equator and ecliptic.  I am showing it when it crosses the equator, hence the seemingly random time listed.

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

Detailed

  When Mintaka was at opposition during the last few days of September, we would beable to see it rise during deep civil twilight, and set before dawn.  Although planets don't have the same type of oppositions as the outer planets, with some being far from the ecliptic, having the Sun at elongations near 180º from them once a year, gives us that chance to watch them move through the sky, and trace out their latitude.  Anyone staying up viewing all night do long-exposure astrophotography of Mintaka could make an image of the star's path.  Relating this to the Moon and getting back to that, our satellite is only about 8 arc-minutes north of the equator at the time above, and crosses it at 12:43 AM.  About an hour and a half later, the Moon is almost exactly the same declination as Mintaka.
   What is even more interesting about the Moon, is that because of precession of the nodes, it crosses the celestial equator at a different longitude each time.  Therefore, different stars have close encounters, or occulted by the Moon for months at a time for some years, and then for other years, the Moon may miss some of the same stars it occulted by over 10º.  Watch the Moon closely in a telescope on some evenings when there is less change in the Moon's (dec)lination, and find that at times, the precession of the nodes keeps it a particular dec for several minutes, of even a few hours.  The benefit of this of course, is that the telescope's dec adjustment--if manual--doesn't have to be change.  In the case of now however, when the Moon is quickly changing declination as shown by the ecliptic, a manual telescope will require regular "tweeking" of the the dec control.  If you have a small, equatorial telescope, particularly one that tracks via an electric motor/gears, you will have the most experience with this, instead of someone else viewing with an alt/az telescope.

Mercury and Mars almost "binocular-friendly"

Event Date: January 29th

Time: 6:00 PM

Brief

   Although we still have to wait until Mercury to get a little further from the Sun to start seeing it easily, we have another planet in the sky that we will beable to see very close to it in a little over a week: Mars, which is still north enough of the Sun to be visible in twilight sky until late February.  By then, Mars will be deep in atmospheric pollution when finally visible, and likely will be hard to see wit the eye.  Obstruction from houses and trees could be a problem, so try to view the pair from a location that allows you to see them set with no hills, buildings or trees in the way.

   Take a look below at the two planets.  Mars (+1.2) is a little more than 9º separated from Mercury (-1.1). 

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

Detailed

   Mars reached perihelion 5 dates ago, and now is slowly moving further from the Sun while still moving further from us.  However, as a result of slightly waxing each day, it will remain the same magnitude for several weeks.  Once it passes conjunction and very slowly emerges into visibility in the morning sky, Mars will continue to spend several months moving away from the Sun.  We will not see it easily visible until very late in the year, a few months from its opposition, although it will be dim as seen in summer and fall morning skies.  As for the pair getting closer, Mercury will be the brighter of the two by far, when they are seen separated enough from the Sun to see easily together.  Can you predict how close they will get and on what date, when comparing the ecliptic latitudes now?  Keep in mind that Mercury's latitude will change rapidly between now and inferior conjunction.  I purposely did not put the orbits in the image to make the prediction a little more challenging to make! 

Jupiter nearing stationary, high in evening sky

Event Date: January 28th

Time: 7:52(.45) PM

Brief

   Jupiter is transiting at a better hour about every two weeks, for the benefit of those who need to go to bed early: whether it be young children needing their sleep, or [older] others being rested for work (i.e. yours truly some mornings!) or any other reason.  At the time above, it is at is highest for the evening, and can be seen not much lower 2+ hours before transit, when it first becomes visible in civil twilight.  The closer we view it to transit, the further out of atmospheric pollution it is.  Take a look here, as I include the meridian and show Jupiter at 73º in altitude, as a result of being 20.8º in declination.

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

Detailed

   Being almost exactly where the Sun is in the sky at the end of April, Jupiter is placed high enough that if viewed an hour before or after transit, it is less than 4 1/2º lower in altitude; hardly noticeable to the eye as seen from most northern latitudes.  Also, if you have kept track of my Jupiter entries in recent months, you may recall that it has been viewed in proximity of the Taurus star clusters: the Hyades and Pleiades.  Also, you may have noticed that it has not changed in position much over the last few weeks, in relation to these clusters.  That is because--as mentioned not long ago--Jupiter is reaching the end of its retrograde, and ready to go stationary.  It has reached elongation 117º east of our star tonight, as we have pulled far enough away from it our orbit and hardly seeing it move west to east against the stars anymore.  During the early morning hours of January 30th, about a degree less in elongation, Jupiter reaches stationary.  This may seem dull to talk about, yet think about this: after it starts accelerating in pro-grade again, it will begin to move slightly more north each day, week, and month.  It will move closer to where the Sun is at the June solstice, and reaches its highest in the sky that its orbit puts it.  By the time it starts its next retrograde in early November, Jupiter will be well into Gemini, and only slightly south of where the Sun is on the June solstice.

Mercury approaches perihelion, north of Sun

Event Date: January 27th

Time: 5:30 PM

Brief

   We previewed Mercury's trek east of the Sun last week, while it was still a couple of degrees south of our star as a result, setting first, among the two.  Now, Mercury still isn't separated enough from the Sun to be unaided-eye visible, yet by next week, that could change.  If you are viewing with an unobstructed horizon, preferably high enough up to see over most or all obstructions such as tall trees and buildings, try to find it.  Mercury sets 28 minutes after the Sun this evening.  Here it is with the setting Sun below, with Mercury's orbit showing.  Note where it is related to the ecliptic, in latitude.

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

Detailed

   Look where the ecliptic crosses the celestial equator, not far east of Mercury.  Because of this, where the next several degrees that Mercury will move in longitude will have it increase in declination.  As it does, approaching perihelion in mid-February and separating from the Sun, the few days before greatest elongation will have Mercury displayed as easiest to see with the eyes.  After all, with the Sun moving a little further north each day and Mercury slowly dimming as it wanes, we want to get the best view of it displayed in a dark enough skies.  The combination of it bright and twilight ending soon enough, will give us the chance to see it with the eye early.  As a good test, try timing how long you need to wait between official Sunset time and when you first see the planet with the eye...even as a very faint dot in challenging twilight.  Right now at magnitude -1.2, this doesn't seem like the most spectacular magnitude for Mercury, yet just wait: as it approaches perihelion, the dimming will once again, be slow.  Combining that with an improving emergence from the Sun over the next two weeks, we are in for an elusive planet treat.

Venus near superior conjunction: getting low

Event Date: January 26th

Time: 7:00 AM

Brief

   As Venus continues to move towards superior conjunction, it is also moving further south of the Sun for a short period of time.  Our star is gradually--yet more quickly each week--moving north towards the celestial equator, while Venus is still separated enough from it to be further south by a few degrees.  As Venus catches up with the Sun in both ecliptic and celestial longitude, it slowly sinks below the ecliptic and therefore, loses declination as well.  Looking below, we see Venus' orbit as it has "swung" the planet from near to far from us since June, closing in on the ecliptic and then a little south of it close the the horizon.

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

Detailed

   There are two times that Venus comes very close to--and eventually crosses--the two nodes: June and December, for ascending and descending respectively.  For the former, we witnessed that one visibly, for the last time this century, when Venus transited the Sun in early June.  Other times, when there is no transit during inferior conjunction, Venus can be as far as 8º north or south of the Sun, which usually happens during the in-between months of March and September.  In the case of this past December, Venus was still separated far enough from the Sun that there was no chance of transiting the "backside" of the Sun (from our point of view).  Also, we should keep in mind that while June and December are 6 months apart, Venus spends about 9 months on each side of the Sun from our view of directions: east and west.

   If you want to know more about transits of Venus across the Sun, or lack thereof each century, you can find that out here...interesting?  It is strange to me, that when so rare each century, that the two are so close together, at about 8 years apart.

Moon's orbit, and more "node talk"

Event Date: January 25th

Time: 5:30 PM

Brief

  The Moon reaches crest of fullness more than 27 hours after the time above, yet it still looks nearly full when rising in the east-northeast this evening.  Although it is rising at about the same longitude as our Sun during mid-July, the Moon is not as far north as our star this time.  Precession of the nodes has brought it south of the ecliptic by more than 4º and therefore, it is only about as far north as the Sun during the first week or two of August.

   Taking a look below, I included the ecliptic and Moon's orbit, showing it being south of our Sun's path.

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

Detailed

   I bent the sky slightly in the image, to show in the upper right, the descending node arrow.  This node, along with the ascending one 180º away in Sagittarius, move a full cycle around the ecliptic about every 18.6 years.  This equals 19.35º a year, and 1.61º per month, on average.  I put these numbers out there, to demonstrate how slow the process is.  The monthly movement is only that of 3 full Moons from us.  However we compare them, they are on the move regularly, hence the word "precession".  About 6 and 7 years ago, the ascending node was near the position in the sky that the Sun is for the March equinox, and the descending where the Sun is for the September equinox.  As a result, when the Moon reached full near the spot where the Sun was at the June solstice, it was about 5º further north, and about as north as it could be anywhere in the sky.  Whereas the Sun only reaches 23.5º N (rounded) in declination, the Moon was nearly 29º, and seen very close to zenith at transit in the most southern portions of the US and northern Mexico, among other locations at 29º latitude.

Arcturus rising late evening

Event Date: January 24th

Time: 12:00 AM

Brief

   During this time of year, we welcome back a bright star to the post-midnight skies, rising shortly before that, as seen from locations west in their time zones.  Arcturus!  I mentioned this star several times at the beginning of this blog last spring, as it marked the center of the Spring "arc", sandwiched by the last handle stars of the Big Dipper and Spica.  The latter doesn't rise until later in the morning, being further south and east of Arcturus.  As for the Big Dipper, it is already high in the northeast before midnight.  The image here shows the Dipper with no stick figure.  Look where Arcturus is low in the north-northeast, and look to its upper left for the Dipper stars.

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

Detailed

   According to this table Arcturus is the forth brightest star as seen from Earth, at about magnitude

-0.04, although it and later-to-rise-Vega are nearly identical in apparent magnitude; the latter only very slightly "dimmer" and magnitude +0.03.  There isn't a noticeable difference through optical aid, and especially with the eye between these two.  At 37 light years away, I can personally say as I write this, that when I look at Arcturus early in the morning sky, I am seeing the light the way it was when I was either an infant, or just before I was born, depending exactly how far the star really is. Stars are usually estimated to the nearest whole value for light year distance.  In any case, I can accurately say that I have lived (about) as long as it has taken for Arcturus' light to go from the star to Earth-viewers eyes...pretty cool!  I passed this already with some other bright stars such as Alpha Centauri (4 years), Sirius (8), Altair (17) ,Vega (25), just to name a few.  The next 1st magnitude star that I can look forward to doesn't happen for a few more years: Capella, at 41 years, which is just "a hair" dimmer than Arcturus and Vega.

   Getting back to the star itself, it has an unusual characteristic which makes it very different than many other stars that we see easily: it is "cutting perpendicularly through our galactic disc".  You may remember when I was discussing the Mayan Calendar topic, that I was showing the galactic equator, marking the Milky Way as it circled around us.  To learn more about Arcturus' motion read this excellent description.  It may seem abstract, yet all we really need to know is that Arcturus will be very slightly closer to our solar system in a few thousand years, yet not noticeably.  More obvious, millions of years from now, we will not see this very fast moving star.  In the sky, it is completely unnoticeable on a night-to-night basis, yet it is happening!

Mintaka: from home, and waaaay, down under!

Event Date: January 23rd

Time: 6:30 PM/2:30 AM (UT-next day, from south pole...read further)

Brief

   This is one of those evenings when I have a bit of blogger's block: does that really exist??  

Rather than take time attempting to come up with a new topic or revisit planets, I will review one of my favorite, visible stars, in reference to its declination: Mintaka.  Read more about it here, including about its companion star.  

   When looking at this western belt-star, it doesn't seem too attractive to the eye, comparing it to brighter or more colorful ones: Sirius, Antares, and easy-to-split doubles such as Mizar, are a few that come to mind.  While these are all in very different parts of the sky, they are also at very different declinations of each other: several degrees south, several degrees north, and even further north respectively, it requires alot of telescopes slewing!  As for our featured star, Mintaka is less than 18 arc-minutes south of the celestial equator.  Therefore, it (seemingly) traces out the equator better than any other easily-visible star, throughout its time above the horizon.  

   Here is Mintaka labeled, shown with the other belt stars and rest of those bright enough in Orion, zoomed in 2 1/2 times to more easily see its separation from the celestial equator.  Except for the Moon, seen between two of the hunter's stars that make up his club, no other celestial bodies are labeled.

Detailed

   If this star was seen looking directly from the South Pole, and there is no obstruction, Mintaka would be the brightest star that is closest to the horizon, moving just above it 24 hours a day, every day of the year.  *Please don't ask me if there actually is obstruction or not, as I have no desire to go there anytime soon to find out! :-) Getting back on topic, remember that--disregarding proper motion and precession of the Earth's axis--all stars seen directly from the poles, are circumpolar: they will never rise or set.  Unlike the northern hemisphere however, where we have Polaris, there is no star as bright, as near to the southern celestial pole.  There are very bright ones (Alpha Centauri and Canopus) that are close enough to guide one in that direction, yet no where as close as Polaris is to the north axis.  

   During months that it is deep twilight or dark at the south pole, those braving the journey and insanely frigid temperature there, can see it.  For fun, I will show this in image two, as the software lets us take it there.  Enjoy being warm(er), while seeing stars from the pole!  Mintaka is labeled, as is the celestial equator, which in this case, is the same as the horizon!  Since it is summertime there now, and the sky is always light for the next 8 weeks, I will put the sky in dark mode...as if it could get any more depressing from there!  I will also hide the landscaping so to clearly see the horizon/celestial equator, and Mintaka, at its northern transit point.  Notice finally, that the numbers on the equator are upside down, as they are--by default--represent the northern hemisphere latitudes!  Hiding the horizon shows something else: an "upside down" Orion...at least, for us northerners anyway!  Therefore, the waxing gibbous Moon, when above the horizon, appears upside down and instead looks like...a waning gibbous!  Weird?  Not really, and especially for anyone who has lived in southern latitudes and never northern ones!

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

    

  

Uranus: following Neptune to conjunction

Event Date: January 22nd

Time: 8:00 PM

Brief

   Yesterday while showing Neptune low, I ended the entry by mentioning another distant planet not far from conjunction: Uranus, that is.  I labeled this "near-twin" of Neptune in the image below.  The two are not much different in diameter: about one of that for Earth, with Uranus larger by about 30%.  They are also both gas planets, along with a color similarity (more on that in the detailed section).  Most importantly, Uranus' movement of speeding up and slowing down against the stars, "independantly using Newton's laws of gravity" helped astronomers find Neptune in a certain part of the sky.  Although I retrieved the above quote from the software itself, read this information.  

Here are the planets labeled.

Detailed

   Once again, as with the image, I will use information from the Starry Night software to talk about the gases and colors of the planets:

"The compounds that give Jupiter and Saturn their color, are frozen in the clouds of Uranus, and we see only the blue-green color from its traces of methane."

For Neptune, the blue color is deeper than Uranus' with almost no sign of even slight-green.  To learn more about the gases and colors of both, you can find that here. 

Neptune's explanation is a little simpler, in my opinion!  In any case, remember that the color we see is the [Sun]light that gets reflected back to our eyes.  Just about any color that we cannot see is instead, absorbed, and do not come back to our eyes.

   Although we lose Uranus to atmospheric pollution and then the Sun's glare, we will have it well placed again for viewing during summer mornings, and fall evenings.  Seen in Pisces, with its "brightest" stars not much brighter than the planet itself, seeing Uranus with optical aid shows a star-field of stars not much dimmer than it's 5.8; most are between 7 and 9, with a 5 or 6 here and there.  Take a look at this image of a 1/2º field (about 100x magnified) to see the stars around Uranus this evening, and for the next few days; how many exactly, depending on the size of field used.

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

                                                                                                                                                                                                                                                                            

Neptune nearing conjunction

Event Date: January 21st

Time: 6:30 PM

Brief

  Over the last several years, January has been the month that Neptune would make its descent quickly to the horizon during the evening; even at the same time as the Sun or shortly after, depending which decade we are referring to.  Now that the Sun is in western Capricornus while Neptune is in Aquarius, that still doesn't give much time at all to find Neptune, before twilight is not interfering.  Since the Sun will start moving north more quickly over the next month, leading to slightly longer twilight time each week, Neptune will barely be visible even with a telescope by this month's end, and then be out of view until late spring/early summer when it gradually emerges south of the Sun in dark-enough skies to view.

   Take a look at the image below, including the celestial guidelines, reminding us that despite a small separation with the Sun, Neptune is still north of it.

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

 

Detailed

 Neptune sets 2 hours, 24 minutes after the Sun this evening, while latitudes just north or south of us see it set within that same range: between 2-3 hours.  Whatever the gap is, it is important to realize that the planet is north of the Sun now, yet setting about four minutes earlier each evening; that while the Sun is setting several seconds later every evening.  The result?  Conjunction is not far away, happening in about a month.  Another distant planet sets not long after Neptune while the night is still young, and will also reach conjunction with the Sun during the early part of this year.  Do your recall which one it is...especially if you have read enough of my past Neptune entries over the last few weeks?  I will reveal the answer--or reminder in the case for some--in tomorrow's entry. As a result, I am not labeling it for this image above.

Jupiter, Moon and Pleiades: together and high up

Event Date: January 20th

Time: 8:00 PM

Brief

   We have an interesting trio to witness this evening, although one of them will be somewhat "washed-out" by another: Jupiter, the Pleiades star cluster, and the waxing gibbous Moon, which is bright enough to make the Pleiades harder to see with the eye.  Although this is unfortunate, the cluster is still easily visible in binoculars, and a wide-field for a telescope.  If you can see the Pleiades with the eye however, viewing the three is fun to do.  Try doing so when all three are near transit, at the time above, and shown below.

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

Detailed

   We are fortunate to see all three of these very high, as seen from our latitude.  At latitudes in the southern U.S., and northern Mexico, the trio is seen at or very close to zenith for each time they group.  Which latitudes see Jupiter at its highest in the sky depends where the planet is in the sky on a coordinate basis; this of course, varies from month to month, and more obviously from year to year.  The Pleiades, being fixed, will always be seen high as seen from our latitude.  As for the Moon, it and Jupiter often pair up, whether it be north of the celestial equator (not shown) or south of it.  Jupiter's 12-year cycle through the sky, along with its change of direction against the stars as seen from Earth, means that each time the Moon is seen to "catch up" with it, the separation varies: sometimes a few degrees apart, sometimes very close.  Every so often, for a few Moon-cycles in a row, it occults the planet, seen from certain parts of the world-- time zone and latitude depending.

   Enjoy the three, and if you miss it because of poor weather, the next one is seen February 17th.  The configuration will happen for the next few months, until Jupiter starts to pull away far enough from the Pleiades late in the year.