final entry: "pre-equinox" special!

Event Date: March 20th

Time: last second of year (3:58.13 AM) PDT.

   Over the last year, since the Sun reached ecliptic longitude 0º, I have had the opportunity to inform, educate, and perhaps even entertain(?) readers from around the world.  I have noticed this, based on the wide variety of countries and territories showing up on my audience/stats page, just to clarify! Hopefully many of them have found convenient time to read as well as view the page.

   In recent years, I have come to the belief to not start something that I cannot finish.  When starting to put my astronomy journal entries onto blog form, I knew that it would be a big commitment to make it work on a daily basis.  As a result of other interests and a very busy work schedule taking up multiple hours, the last few months have been a struggle to keep up with the blog, and the upcoming months look to be even more difficult, without falling behind.  With that said, the last two days of summarizing the planets' positions in the sky with their celestial paths, will be my final entries, having rounded out the astronomical new year by date.  Today, as the Sun crosses ecliptic longitude 0º again, I am posting an image from the final second before that happens, shown below.  The ecliptic-related lines are in bold green, while I kept the still-important celestial-related lines thinner and dimmer.  Once again, this is a fitting image, as the Sun is less than 1/1000 of an arc-minute from 0º ecliptic longitude.  As a reminder, although the celestial meridian (0h) seems to intersect at the exact same spot and the Sun seems to be exactly bisected by it, the two don't exactly intersect, and the Sun passes 0h a little more than 6 minutes earlier.

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

   Overall, thanks for joining me on this astronomical journey between the two March 20ths during 2012 and 2013.  I have tried to keep the variety alive by including star characteristics, constellations, deep sky info, and of course, our solar system "family" of the Moon, Sun, planets, and their satellites.

   Although I don't plan to continue to blog daily or even somewhat regularly for an indefinite period, I won't close any doors, and will keep the blog online for anyone who wants to read entries during the past year's worth of dates.  There is definitely some variety, so please feel welcome to take a look back and do so.  In the meantime, I will continue to use some of the time not blogging to use the software to find extra "oddball" stats and alignments in our solar system, galaxy and universe.  If by chance those compulsions to share my findings churn inside of me, I know that I have my blogpage to share them with!

In the meantime, while not blogging, I will be busy with other life doing and findings as well.  Find me on Facebook and Twitter (@DavidLikuski).  Thanks again, for reading and hopefully learning a thing or more, about the abstracts, characteristics, and occasional trivial facts about what we see in our sky!

outer-planet year-long recap/look ahead

Event Date: March 19th

Time: various

  I will continue with the planet summary that I started yesterday.  That one included the inner planets with orbits on both sides--for lack of a better word--of ours. This time, I will do so with the outer planets.

Jupiter We will continue to see the king of the gas giants easily for about two more months-worth of weeks with a telescope, before atmospheric pollution makes its features hard to see.  It spends one more month east of the Sun befoe its near-solstice conjunction in late June.  Jupiter continues to pick up speed in prograde motion, and will be near the Gemini border at the time of conjunction, very close to where the Sun is at the June solstice.

Saturn is the only planet in our solar system improving in apparition during the spring, with its opposition coming up next month.  Its rings are still easy to see, despite retrograde motion leading them to tilt very slightly away from our line of sight.  As a result of the excellent tilt this year and the next few, Saturn's opposition magnitudes (brightness-wise) are better than those from much of late last decade.

Uranus and Neptune: spread gradually apart between now and this time next year, as the former moves faster against the stars in its smaller orbit.  Both will become [morning] telescope targets again this summer, when they separate far enough from the Sun and out of the way of twilight.

*Now, for anyone who wants to count dwarf-Pluto, it will remain almost unchanged from its position last year, in Sagittarius, where it slowly creeps across the archers stars over the next few years.  It is visible in a telescope for a short time between escaping atmospheric pollution and twilight gets in the way.

Once again, here is the celestial path of each planet since the March equinox of last year.  Also, increment markers are again, 10 days apart.  Notice how much closer the markers are as we get further and further outwards towards Neptune.  Unlike the inner planets, the whole year-round path, both prograde and retrograde, is visible.  Jupiter had its retrograde late in the [calendar] year and early this one.  Saturn started out with retrograde and back at it now.  Notice that with the the sharp inclination of Pluto's orbit (not shown so to not interfere with the path), that the change in direction has it at very different ecliptic latitudes while at the same celestial longitudes.  Although the images are zoomed out and this isn't too noticeable, compare it with the other outer planets' paths, and there is a difference.

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

inner-planet year-long recap/look ahead

Event Date: March 18th

Time: various

  As we round out the astronomical new year tomorrow and part of the 20th (up to the exact minute of the equinox), I will do a brief summary of the inner planets' positioning today, including images of where they are in the sky.  I will also show their celestial paths, as a reminder of how their revolution periods have us see them moving against the stars.  As a result, no brief/detailed sections here.  I did this not long ago with a few of the planets, yet this time, will cover all of the "classical" 8, in two separate entries.  Here it goes!

Mercury: as mentioned the last two entries, it is now emerging further from the Sun in separation, with its poorest morning apparition of the year for mid-northern latitude viewers.  This follows two very good apparitions, with one previous morning one and these two sandwiching an evening one with the planet at perihelion.

Venus: Nearly at superior conjunction, the planet will not be easily visible to even the eye for another two months.  By then, the late Sunsets mean that we will have to wait until late-evening hours to see it easily with the eye.  We will have the planet east of the Sun for the remainder of the calendar year, with the geometry of the western sky varying greatly during that time.

Mars: As the case with Venus, our other "neighbor" planet will be at conjunction very soon.  Unlike Venus however, much dimmer Mars will not be easily visible to the eye until late in the year.  It will be a victim of poor, morning eastern sky geometry, while taking several weeks to emerge from the Sun.  Opposition happens early next year, yet until only about two months before then, Mars will only appear like a dull star to the eye.  

Now, for the images:  Aside from the retrograde "loop" for Mercury recently, the paths look very similar.  Look at the increment markers however, 10 days apart: despite speeding up in prograde motion, leading to the markers spreading out, Venus has done the same.  Therefore, the latter's markers are further separated.  If I was able to show the entire 360º of azimuth (i.e. looking straight down towards and through zenith), I would beable to show the interesting retrograde paths of the planets.  However, I have shown those enough times this year that if you want a reminder, just refer back to past entries this year.  Although I haven't plotted paths of each for all of those entries, just think back to how the planets have moved against the stars.  Rather than rely on software and internet sites the whole time, also view the planets with your eyes, and enjoy them passing near stars!

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

Mercury: current from mid-southern hemisphere

Event Date: March 17th

Time: 6:00 AM

Brief

   I ended yesterday's entry about Mercury's poor morning apparition with a glaze-mention of how the planet would be seen from many southern latitudes.  True, the apparition would be much better, and Mercury will have a wonderful greatest elongation.  As I have a couple times, in nearly a year of working on this blog, I will pick a southern hemisphere latitude precisely equal to ours here in the northern hemisphere.  Once again, I will choose Box Hill (Victoria) Australia, which is our latitude in the southern hemisphere, of 37º 49'.  They are 19 hours ahead of us, if using daylight savings time.  Therefore, with the change in date, I simply forwarded the clock ahead 5 hours and turned off daylight savings.  Take a look at Mercury's orbit, and how the angle of the ecliptic with the horizon.

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

Detailed

  At the date and time listed, Mercury is already rising one hour, thirty nine minutes before the Sun.  On April 2nd, the rise gap is 2 hours, 18 minutes.  To put that in perspective, that is bigger than the Sun and Venus sometimes, when Venus is closer to conjunction than greatest elongation.  With such a gap, Mercury will be 26º in altitude at Sunrise!

   Despite the southerners getting such a great apparition, let's remember another reason why, besides the excellent geometry of their morning sky at this time of year: Mercury being near aphelion.  As a result, the planet doesn't brighten much until several days later, when it quickly starts moving towards conjunction.  It will not be until the end of April and early May that Mercury's magnitude dramatically improves for viewers there.  By then, we will start looking forward to it coming back into our evening sky.  For that one, given that it will be nearly winter for the southern hemisphere, they will have a decent apparition, while we will have a fair one; the problem for us "notherners" of course, will be having to wait for the Sun to take a long time to go down, longer twilight, and Mercury eventually falling south of the Sun as it did here in the morning sky.

Mercury's worsening apparition...or improving?

Event Date: March 16th

Time: 7:00 AM

Brief

   Today's subject header may seem misleading.  However, it depends from which latitude(s) in the world Mercury is being viewed from!

   Although it has separated quickly from our star, Mercury has also moved south of it very quickly.  Part of the reason of this is that the Sun is moving northbound at its fastest this week, nearly at the celestial equator, which it reaches on the 20th.  As for Mercury, it has also been a victim of the Sun's glare.  Taking a look below, is Mercury with its orbit and the celestial guidelines.  Notice how much more of the orbit's "loop" sticks above the horizon, compared to when it was at greatest elongation back in mid-February; a reminder of that can be found here.

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

Detailed

As it has separated from the Sun, Mercury has also moved closer to aphelion, which it will reach at the end of the month.  By then, the planet will be near greatest elongation and therefore, moving slightly away from us, while moving further from the Sun.  At that point, we will only see it at about dichotomy, Mercury will remain a dim magnitude for almost all of this time west of the Sun.

   As for this morning, Mercury rises 56 minutes before the Sun, and is already about 6 1/2º south of it.  That may not sound like much of a declination gap, yet it will grow quickly to almost double that during the few days of next month, during the week of aphelion.  The magnitude of Mercury will be almost opposite that of the greatest elongation in February: +0.3 instead of -0.3.  Once again, if that doesn't sound like a big difference, you are right.  However, considering that the February elongation had Mercury isolated in an astronomical-twilight sky about 4-6º above the horizon (exact mid-northern latitude depending), this time the planet will be nearly buried in the glare of a much more northern Sunrise in comparison.  If we combine the multiple factors of this worsening morning apparition of Mercury during March, one thing remains almost the same for about three weeks: the rise gap.  Considering that Mercury is separating from the Sun while becoming further south, that makes sense.

   In short, it is not a good showing of Mercury for much of the northern hemisphere.  For the southern hemisphere however, it is the best morning showing of Mercury this calendar year.  The planet rises over two hours before the Sun at and near the time of greatest elongation.

Arcturus and Vega at same altitude

Event Date: March 15th

Time: 5:43(.17) AM

Brief

   I mentioned Vega yesterday with a reminder of the Summer Triangle.  At magnitude 0.0, it is the 5th brightest in apparent magnitude.  Although the 1st through 3rd brightest are all below the horizon, being Sirius, Canopus and Alpha Centauri respectively, the fourth brightest is well above the horizon, being Arcturus. 

UPDATE: these latter two have been flipped in brightness order, according to the Wikipedia list, and Arcturus being a variable star.

  Although Arcturus' and Vega's nearly identical magnitudes make them seem "twin-like, they are very different in another way: Arcturus is a an old red-orange giant, while Vega is a much hotter blue-white star.

   The image below shows the alt-az grid, and both stars at nearly the same altitude.  They are just slightly over 60º 4' above the horizon. 

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

Detailed

Although it requires a close look, the software is set up to show each star's color when zoomed out.  As mentioned yesterday, Vega is 38º north, while Arcturus about half that declination.  As a result of that, we see Arcturus less time above the horizon.  For southern hemisphere observers, those in locations where the stars clear the horizon, would see Arcturus longer than Vega during certain times of the year.  Every day, about four minutes earlier, these two stars reach the same altitude.  The only thing that also factors into this is their proper motion, which means a change in about one arc-second every six-seven weeks (declination) and about a 10th of a second (s) in r.a. every three weeks.  Despite that, we will see them at the same altitudes for the rest of our lives, and they will continue to for years to follow.

Summer Triangle: higher before Sunrise

Event Date: March 14th

Time: 7:30 PM

Brief

   As we near the March equinox, it is a reminder that Summer also isn't far from now.  With that in mind, the namesake triangle---which I have featured countless times (it seems anyway)--is now well placed in the east.  With daylight savings time now in effect, we can spend the next few weeks not having to wake up quite as early to see the large asterism.  However, with the Sun rapidly moving north and our earliest Sunrises only about 2 and a half months away, it will eventually mean waking up early enough to see it.  Or, for the night owls out there, simply stay up late enough!

   The image shows the triangle's center almost directly east.  If you forget how to find that, refer back to this entry.  

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

Detailed

   

   Vega already rises before midnight for most mid-northern latitude locations, with Deneb to follow shortly after.  Altair follows suit a little two hours after Deneb, depending exactly on one's latitude.  For our location at this time shown above, Vega is only a little over an hour pre-transit and about 75º in altitude; that is almost exactly how high the Sun gets at transit on the June solstice.  Of course, the Sun's maximum declination is about 15º south of Vega's maximum (nearly zenith), so it may be a strange comparison.  In any case, if you can still see Vega long enough during twilight, being almost exactly magnitude 0, it can be seen transiting.  Get a telescope on it if you want to view it long enough to see this.  In about another month, the star will have risen early enough to transit before the middle of civil twilight, which is about the time that most of the brightest stars become impossible to see with the eye.

   

comparing the outer and inner planets' visibliity

Event Date: March 13th

Time: 7:30 PM

Brief

   This is a quiet time for our closest-neighbor planets when it comes to trying to view them: Mercury, Venus and Mars are all near conjunction, or in the case of the former, emerging low in the glare of twilight.

     With that said, as we wait to see these three again, we have Jupiter getting low in the west each day, and Saturn rising during mid-evening hours, not far from opposition.  As shown about a week ago, Saturn and Jupiter are very slowly closing in on each other between now and late 2020.  The two images are reminders of where they are in the sky.  The first shows Jupiter as if we were viewing with our eyes looking left-- of the north celestial pole; see more in the detailed section.

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

Detailed

   Within the boundaries of Taurus and headed towards Gemini, Jupiter continues to gradually increase in declination.  The next time we see it transit far enough from the glare of the Sun, or during dark hours, it will be about as far north as it will get for the next 12 years, and be very close to where the Sun is at the June solstice.  As a result of that, viewers in the far southern U.S. latitudes and some in Mexico, north-central Africa and far-east island-countries will see it at or near zenith during some dates during this year and next.  Its switching from pro-grade to retrograde and back again keeps it at the Taurus/Gemimi border for awhile.

   As for Saturn, it is about half as far south, as Jupiter is soon to be north.  Saturn rises not long before midnight this week.  Its elongation with Jupiter is large enough that we have to wait until Jupiter sets before seeing Saturn.  However, that gap will shrink several degrees each year and by about 2018, we will see both giant planets near each other in the same part of the sky.  A magnificent close encounter happens, and it will be extremely telescope-friendy under low magnifications (between 50-70x).                                

When and why do we see the "devil" Moon?

Event Date: March 12th

Time: 7:30 PM

Brief

   A few years ago, the late February-early March waxing crescent Moons had great apparitions during their first 48 hours.  Our satellite's orbit was just past ascending node west of it, and it moved north quickly.  Now, as shown in the image below, the Moon's orbit has it coming fast towards descending node.  Even though our satellite still moves north quickly, the rate of that decreases faster than it did at these same longitudes back in between 2008-'10.  Notice how the orbit's angle with the ecliptic is smaller by a small amount.  Regardless, the sliver of Moon that we will see this evening will be impressive.

Detailed

   The second image that I will show, is that of the Moon seemingly "sitting" on its western limb, looking like a small smiley mouth.  Take a look to see what I mean.  

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

Others have dubbed this appearance as the "horns" or even more interestingly enough, the devil horns.  I have yet to find a link for the latter, although one for the former is here.  The terminator creates this image of two pointy (sharp) horns sticking up.  This is more properly known as the cusp.  This is the case because--as we see them--the Sun is shining at the Moon from almost directly below the horizon.  There are other times when the Sun shines on the Moon's side instead of its front, and it appears like a backwards "C" shape.  There are also rare times--when its azimuth is a little closer to north than the Sun--that its smile shape is tilted a little to the right from our perspective.  This happened a few times over the course of 2011-2012, and it is as if we are viewing the waxing crescent from the low-mid southern latitudes in August and September.

In short, the Moon's apparent "tilt" depends mainly on the geometry of the sky and a few times, where it is in ecliptic latitude.

Big Dipper pointer stars: same altitude

Event Date: March 11th

Time: 8:31(.25) PM

Brief

   I have shown the Big Dipper's "pointer stars" Dubhe and Merak several times, leading almost directly to the north celestial pole; even moreso to Polaris, which as a reminder, is 40 arc-minutes from the pole.  This evening, I will get a little fancier with the dipper stars.  If they can point together towards another star, how about pointing towards... each other??  Okay, that may sound weird, yet what I am referring to, is their altitude.  With an altitude/azimuth telescope, a viewer--for the fun of it--can slew from one star to the other at the time above.  At about 5.4º apart, they are just over 44º high.  Notice that at our used-latitude of just under 38º, this is a little over 6º further north than the celestial pole.  Therefore, it verifies--by number--how far the stars point away from the pole and namesake star.

   Here is the Dipper and stars.  I chose an azimuth almost directly between them, to show that the part of the stick figure that connects them is almost perfectly straight.

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

Detailed

   We have seen the Dipper with these stars at this position in the sky at later hours of the evening and early hours of the morning over the last several months, heading backwards in time.  Since the asterism is circumpolar to us, it depends what time of year it is for us to see it most frequently in the northeast this way, seemingly standing on its handle [stars].  Other times, we see it high in the north, and looking as if it pouring out content of some sort.  Finally, when seeing it in the northwest, it looks as if it is almost resting on its cup, with the handle curving down towards towards Arcturus and then (if still above the horizon at the time) Spica.  Of course, I am talking about the spring arc asterism, which beginning next month, spends the entire evening above the horizon.  I will review the arc in after the equinox.  Until that time, enjoy the shape and positioning of the Dipper.  Watch how slowly it moves during the 23 hours, 56 minute (sidereal) day.  To go 360º around the pole, that means about an hour to go 15º.  This may not mean much to us, except that when watching it, we hardly notice movement until several minutes later.  Of course, the Dipper and all other stars don't move that fast in that sky: we are.  Thank goodness for tracking telescopes to (sarcastically) eliminate such confusion!

Jupiter and Sun: decreasing in separation

Event Date: March 10th

Time: 8:21(.13) PM (PDT)*

Brief

   As we reach daylight savings* on this date at 2 AM, we are also at a time of year when the gap between Sunsets is getting close to its largest; as are the rise gaps.  I showed this yesterday, with a reminder of how much faster the Sun is moving north towards the celestial equator.  As a result of the evenings staying lighter, it means that we are waiting a little longer each evening to see Jupiter.  When we do, it is a little lower in west.  The first image shows the planet's position looking west-southest, still high enough to view, setting after 1 AM.  The second image shows the path of Jupiter over the last 7 months, since we saw it rising in the east during evening hours.  Notice the pro/retro/prograde switches in orbit, with the markers on the path 10 at 10 day increments.

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

Detailed

   Notice above with the celestial path, how we view Jupiter's plane at a little different angle over the last few weeks, as it picks up speed in prograde.  Fortunately, the planet is moving faster in west to east against the stars each day, between now and conjunction.  As a result, the conjunction seemingly gets "delayed".  One other reason for Jupiter to be "escaping" the Sun for a little longer than we sometimes notice, is that the planet is moving a little further north during this span of evenings.  By the time it reaches conjunction, it is about as north as it can get, disappearing into the Sun's glare shortly before the June solstice.  Unfortunately, once the Sun sets, twilight lasts a long time as our star only gradually sinks below the horizon.  Therefore, even a month before conjunction, seeing bright Jupiter with the eye alone means a little patience, and not minding that it is low in atmospheric pollution by the time the sky darkens enough.  Until then, Jupiter continues to gradually shrink and detail of the belts and zones becomes a little less clear on even the best seeing nights of still, clear air.

   Finally, in case you are wondering, conjunction happens early the morning of June 19th at 9 AM PDT.  When you look at the Sun through a telescope with a safe filter, keep in mind that Jupiter is almost directly behind it; a fraction of a degree further south, so close to its southern limb.  

Sun nearing celestial equator/equinox

Event Date: March 9th

Time: 8:21(.13) PM

Brief

   Back on February 18th, I mentioned--and showed--the Sun at (e)cliptic (long)itude 330º, indicating the beginning of the final sector of the astronomical new year.  We are more than halfway between then and the March equinox.  As shown below, and comparing to the image for that entry, the Sun has made very fast progress towards the celestial equator, and it will continue to move a little faster each day in declination.  Take a look here.  Notice the Sun is only about 3.8º south of the equator, while only 11 days to go before the equinox:

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

Detailed

   Since daylight savings time begins tomorrow at 2 AM, we will not only have a shift in Sunrise and Sunset; we will have close to our latest Sun transit as well for the year.  The transit time of the Sun changes, based on the time change of Sunrise and Sunset, in combination with the length of time it is above the horizon.  Since the Sun is not centered in the orbit, the different speeds that the Earth moves relative to how close it is (perihelion) or how far it moves (aphelion) from the Sun.  

   Getting back to today's topic, it relates to the aforementioned transit one, because the Sun is rising more minutes earlier than the Sun is setting for about the next two months-worth of weeks.  As a result, the transit time will be slightly earlier each day until mid-May.  At that time, being a few weeks prior to the earliest Sunrise, the early rise-gaps start to decrease while the set-gaps continues to increase until late June; a few days following the solstice.

Mercury emerging west of Sun: dim and low

Event Date: March 8th

Time: 6:00 AM

Brief

   We just saw Mercury have its best evening apparition of the year, regarding declination difference with the Sun.  Mercury was a wonderful sight to see the few days before both greatest elongation and perihelion.  Now, as it slows down in retrograde on the west side of the Sun, Mercury is starting its poorest morning apparition of the year.  It only gets worse as the planet stays on this side of the Sun, between now and the days after greatest elongation.  I will explain more about that in the detailed section, following this image of Mercury with the celestial equator, ecliptic, and its orbit.

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

Detailed

   The first thing to take note of is Mercury's ecliptic latitude: we are viewing its plane from an angle, which lets us see it over 3º north.  It was because of this good latitude, that during its previous apparition in the evening, the ecliptic didn't have to have the best angle with the horizon.  Now, as Mercury swings back towards the other side of the Sun, it will stay there--from our perspective--for a little over the course of a little over two months.  The planet reaches aphelion in a little over a month from now, which is about the time of its next greatest elongation.  As it approaches that point, retrograde has already ended, yet not before the planet falls far enough south of the Sun to be in the glare of it for most of this apparition.  

   Of course, most southern hemisphere viewers will love this apparition.  For them, Mercury will not only be about as far separated as it will be all year; with favorable geometry, certain latitudes there see the planet set a little over 2 hours after Sunset, and well out of the atmospheric pollution.  As for us, with unfavorable geometry and a Sun rising over a minute earlier each morning between now and about late April, we are best off seeing Mercury for its next morning apparition, when the declination is about the same during the days sandwiching that of greatest elongation.  Until that time, try to find Mercury in a few weeks with optical aid, and with the eye a couple weeks after that.

Gemini seen high-- its "head" stars aligned

Event Date: March 7th

Time: 8:21(.13) PM

Brief

Castor and Pollux, the Gemini (twin) head stars, are about 4 1/2º in separation.  As seen from our latitude, they are not far from zenith during 20 minutes sandwiching the exact transit time, before and after.  For the second image below, I have set a time for when the two are not only high in the sky shortly before transit; they are the exact azimuth.  Why does this matter?  It really doesn't, since they are easy enough to slew from one to the other with no optical aid with the a telescope.  This is just one of those nights that I have little else to write about, and decided to get silly with crazy star patterns and alignments to the horizon!

  Here are the two stars with the the entire constellation seen high in the sky, followed by a zoom-in of the two with the alt-az grid.  Looking at the altitude lines, notice that the spacing of the stars between the lines is almost exactly the same.  If using binoculars, hold them steady and level to the ground, noticing that the two stars are in line up-and-down with each other.

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

Detailed

   When we see the stars rise in the east-northeast, they are similar in azimuth already.  When we see them setting more than 15 hours later, they are much different in azimuth and more similar in altitude.  Most mid-northern latitude viewers see it this latter way, as the northern stars circle around the celestial pole each day.  At declinations 28º and 32º for Pollux and Castor respectfully, they are further north than the Sun at the June solstice when it comes near them.  Castor is seen a little closer to zenith at southern US latitudes, and transits (near) there.

   As a multiple star system, Castor has two components, which coulde be seen with the unaided eye if they didn't orbit so close to the star!  A powerful enough telescope can split them however, as they are only 4.4 arc-seconds from Castor.

   Pollux is not quite as interesting.  Unlike hot, younger Castor, Pollux is an old, dying star, already a yellow-orange color as a giant.  It is 10 solar radii large, which isn't too big compared to some stars (especially Antares, Betelgeuse and some other red giants), yet it is likely still growing bigger.

Find out more about both stars at this link: 

Jupiter and Saturn: will "opposites attract"??

Event Date: March 6th

Time: 11:36(.05)PM

Brief

   Alright, so you may be thinking that subject header for this entry--which I came up with on the fly in about 15 seconds--is awkward and perhaps wondering what it has to do with astronomy.  There is a connection however--albeit an abstract one--with what I will talk about here!

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Almost 12 years ago, May 28th 2000, Jupiter and Saturn had a separation of 1.1º.   A little over 10 years later on August 13th of 2010, they were at their furthest separation possible, at opposite sides of the celestial dome.  Since then, faster Jupiter has closed the gap and has started to catch up with Saturn in orbit.  

In regards to my header, are you catching on yet?? Let's examine further.

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   The image below shows 180º of celestial dome, while Jupiter sets and Saturn rises.  Each day as it catches up with Saturn, this month specifically, the gaps between Jupiter's [prograde] setting times are larger than Saturn's [retrograde] rising.

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

Detailed

At 152.8º separated and shrinking, both planets are 12º 37.4' in altitude at the time above.  If you have an alt/az telescope centered on Jupiter about a minute earlier, slew it in azimuth only to Saturn over the course of a minute or less, and Saturn would appear in the field at about the same centered spot as Jupiter.  This is a fun thing to try because each evening, the precise-same altitude for both will be slightly higher.  The opposite would hold true if Jupiter was currently in retrograde and slower Saturn in prograde, although such would mean that we would see them "flipped" in the sky at this time of night; Jupiter rising and Saturn setting, that is.  Jupiter's retrograde at peak is not much slower than its prograde.

   The rate of catchup each year until their next encounter depends on which planet is in prograde or retrograde motion.  In some cases, one may be moving one way to another while the other is stationary.  Jupiter has started to pick up speed in prograde as mentioned in recent entries, while Saturn is starting to increase in retrograde.  As a result, Jupiter is starting to catch up a little more quickly than it was even a week ago.  Can you predict when Jupiter catches up with Saturn?  The separation at closest encounter will even differ from the Y2K aforementioned, since it will happen in a part of the sky where the orbits for the two will be closer or further from each other.  Can you figure that part out too?  I already looked up the answer, which I will obviously not reveal here.

 If watching Jupiter close in on Saturn annually, give it a try, and see how close you come in predicting correctly!

Draco, and a former pole star

Event Date: March 5th

Time: 12:00 AM

Brief

  A couple of days ago, I showed how Canes Venatici "chased" the two bears in the sky-- even though it appears as if only the case with Ursa Major.  While doing so, I included the illustrations for them.  I will come back to the bears for tonight, and show another animal in that part of the sky: Draco, the dragon.  Although a faint constellation, Draco's figure is long, and seems to curve around half of Ursa Minor and the north celestial pole (n.c.p.), precisely 39 arc-minutes from Poloris.

   Let's take a look below, and notice how for at least the illustrations used here, that there is a slight overlap of Draco and Ursa Minor.  Their boundaries of course, do not overlap, although the space between the stick figures and stars are very close to each other.

Detailed

   In the second image, I will point out a very key star in Draco, named Thuban. Although not very bright at magnitude 3.6 , it is enough so under dark enough skies that about 4,800 years ago, Thuban was close enough to the n.c.p. that it was the pole star.  In about 21,000 more years, it will be at that declination once again (26,000-5,000).  Back then, centuries before serious light pollution, it would have been easy enough to see Thuban.  I am not sure how popular star-gazing was then, and astronomy in general.  However, whether building pyramids in Egypt or one empire in the process of conquering another(?), looking at the sky under dark conditions would haven become popular then and there.

   In the image, besides centering Thuban I included the precession cycle, which is labeled by certain key years.  I took away the illustrations and kept the stick figures.  Also for anyone wondering, the closest that Thuban was to the n.c.p. then was very close: 89º 53' 56" the middle months of 2800 BC.

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