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.