More on Uranus and Neptune

Event Date: April 2nd
Time: 6:00 AM

Brief

Yesterday I talked about the unaided-eye planets, while today, I will mention the more distant planets: Uranus and Neptune--both gas planets as Jupiter and Saturn are, yet about half the diameter of each respectively.  Uranus is just past conjunction and Neptune is barely visible above the horizon before dawn skies wash it out.  Uranus will be more easily visible by late spring, while dimmer Neptune is far enough separated from the Sun to see before that.

Detailed

A 6 or 8-inch telescope referring to the primary mirror diameter (or lens for refractor telescopes) is recommended when trying to find Neptune, although it will look like just a dim star.  In about a month, when it rises about two hours earlier than now, it will be a little higher before the Sun's light.  It is best of course, to view Neptune near the time of its transit, which will be more easily visible with no Sun glare this summer and fall: transit is the highest that we see a star, planet, Moon, etc. when looking directly north or south (declination depending).  The more north in celestial latitude that a body is, up to the equivalent of our global latitude, the higher we see it in the sky.  I will get into transits more tomorrow.  First, I will show a star not far from Uranus which is bright enough to help guide us to it.  The star marks the tail of Capricornus, the Sea Goat, and named Deneb Algiedi.  At less than 9º from Neptune, the planet was alot closer to Neptune a couple years ago, when passing from Capricornus to Aquarius.  The star is magnitude 2.8, so can be seen briefly this morning with clear skies with binoculars. 
The first image shows Deneb Algiedi and Neptune zoomed out, while the second image shows Neptune alone zoomed in with a 1º field.  Although this indicates a zoom-in of about 50x, Neptune at over 2 billion miles away looks just like a tiny dot.  How easily can you see it?

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

Planet positions: now and through the spring

Event Date: April 1st
Time: 5:00 AM/8:00 PM

Instead of doing a brief and detailed section today, I will summarize the eye-visible planets' positions in the sky; that, and how long we will see them easily.

Mercury is the hardest of all of them to see at times when it is (a) too dim; (b) too low to the horizon while buried in atmospheric pollution; (c) in the Sun's glare.  See yesterday's journal (include link) for more about Mercury and its apparition.

Venus is the easiest to see, and continues to approach its peak apparent magnitude, happening later this month; that being, while east of the Sun and setting about four hours later. 

Mars is just past opposition by a few weeks, and well placed once the sky darkens enough.  Although it has fainted quickly as we move further away from it in our smaller orbit around the Sun, it still outshines all stars around it, including Regulus as the brightest in Leo. 

Jupiter is bright, although becoming harder to see over the next few weeks, as it gets further into the glare of the Sun.  Also, as the Sun sets later and twilight lingers longer, it means that we have to wait a little longer to see Jupiter wit the eye alone. Jupiter reappears west of the Sun as a morning target during the last weeks of spring after conjunction, and becomes a good morning target throughout the summer.

Saturn is easily visible in the late evening now, and soon to reach opposition by mid-month.  It slowly brightens, although not nearly as dramatically as Mars does.  Saturn after all, is much further away. 

Image #1 shows the evening planets, with Venus and Jupiter in the west.  While Venus remains high in the sky at Sunset for about one more month, Jupiter gradually seems lower each evening, when it finally becomes invisible to the eye alone.

Image #2 shows the morning planets, also in the west, as Mars sets shortly before dawn and Saturn not too far behind, being further south.

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

   Mercury, as shown yesterday, rises only a short while before the Sun, and as mentioned, is too dim to see.  In about two weeks, when Jupiter is still visible before conjunction and Mercury emerges from the Sun while brightening slowly, we will have a small "window" of dates to see all five planets with either the eye alone, or binoculars.  Let us hope that conditions are clear enough.
In both images, the ecliptic and celestial equator show, illustrating which planets are further south or north of each other, as well as the comparison to the Sun in ecliptic latitude.  Notice also, once again, where the planets are north or south of the celestial equator based on where they are in ecliptic longitude, although ecliptic latitude can affect their overall declination.

Mercury: poor morning apparition

Event Date: March 31st
Time: 7:00 AM

Brief

One planet that I have hardly mentioned, in the short time that I have done my entries in blog-form, is Mercury.  Shortly before the equinox, Mercury was easily visible in the western sky, for its best altitude above the horizon for the year--and still easily bright enough to see with the eye!  Although it has been faint, and too close in separation to the Sun to talk about over the last 12 days, just think back to what I said and showed with Venus; to get an idea of why Mercury is more visible in the late winter and early spring when looking west.  The planet was more north of the Sun, and at our latitude in this northern hemisphere, that means that it didn't sink below the horizon as soon as the Sun.  Now, Mercury is rising in the morning sky, having passed inferior conjunction, between us and the Sun. 

Detailed

   Mercury will not be easily visible for most of the time that it is seen west of the Sun, until late May, because of a few reasons:
(1) it is now south of the Sun, and therefore only rising a very short time before our star;
(2) the Sun is currently moving north quickly at this time of year, while Mercury is moving further south of the Sun in retrograde motion for a few more days.  As the Sun moves north, twilight time increases, with Mercury not brightening fast enough to be seen without the help of optical aid;
(3) the planet is moving towards aphelion during this time west of the Sun, meaning that even though it is waxing in phase, it will be far enough from the Sun compared to mean distance, that we don't have alot of Sunlit surface area facing us.   
   In short, this is not a good time to easily see Mercury.  By the time that it finally reaches superior conjunction and starting to move back towards perihelion, we are already near our most northern Sunrises of the year, washing out Mercury shortly after it rises.  By then also, Mercury's separation with the Sun shrinks enough that it is in the glare anyway.  When Mercury sets after the Sun again during the first half of Summer, it will be a little more visible and higher, yet not by much.  Our next best time to see Mercury very well, will be the next time that it is a morning target and eventually more north of the Sun.
   Image #1 shows Mercury as it appears shortly before Sunrise, and not long after it rises.  Because of atmospheric pollution and only magnitude +2, it will be nearly impossible to see without a telescope, and a flat horizon would be required with very clear skies.  Image #2 shows a zoom-in of the phase Mercury is now: a waxing crescent.  It is magnified by about 300 times, to show the crescent shape more clearly.  It will remain a crescent until about the time of greatest elongation in April.

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

   Try using optical aid on Mercury at about that time or shortly after, although it will still be difficult to find.  It will not be visible to the eye until early May, when it starts to brighten a little more, and catch up with the Sun a little more in northern declination.  The showing of the ecliptic and celestial equator indicate Mercury being more south of the Sun, while its orbit shows where it is in relation to the ecliptic.  Reminder: the software does not show as much Sun glare as we will see in the sky.

Saturn's moon movements, with Titan empasis

Event Date: March 30th
Time: 10:00 PM

Brief

Yesterday, I showed Saturn and its Moons.  Each night when we look at Saturn, we see the Moons revolving at different rates around the planet, the same way that they do with other planets.  With Jupiter as a good example, we have the Galilean moons, which I will start showing again during the late spring when the most giant of our solar system planets comes back into view from behind the Sun and its glare.  First, I will repost the image from yesterday of Saturn (500x magnified) and its moons, followed by one exactly 24 hours later: notice the changes.  In the second one, the image also has the orbits, to show that the moons are either coming from behind to in front of Saturn, or vise versa.

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

Notice the changes?  As I showed with Venus' orbit in one of last week's entries, the orbits for the Moons have a 3-D look to them: brighter where closer to our line of sight, and dimmer where further.  Just as I mentioned yesterday that we are looking at Saturn from a mid-latitude as opposed to the equator, the angle that we see the Moons' orbits indicates that.
   
Detailed

   Titan, which is seen with a separation of 3 arc-minutes from Saturn's disc center at furthest from our perspective, is the largest and brightest of the Moons.  It is the only large Moon, although even bigger than our planet Mercury.  Even more interestingly, Saturn's slightly orange-ish color indicates an atmosphere that is too thick to show any features. 
   The Cassini Mission, visiting Saturn in late 2004, led to the Huygens probe landing on Saturn in January 2005; I remember the news about that clearly, and how one of my volunteer colleagues at Chabot Space & Science Center enthusiastically showed images to the public on a weekly basis!  Despite an atmosphere being predominantly of nitrogen (90%) and carbon, methane could also be found in the form of liquid methane.
Learn more about Cassini and the Huygens probe here, with images and videos included:
http://sci.esa.int/science-e/www/area/index.cfm?fareaid=12

Saturn: ring-view angles and Moon count

Event Date: March 29th
Time: 10:00 PM

Brief

Saturn is a favorite planet of millions of people, even if it just means seeing it in a book or website. However, once a viewer looks through a telescope and sees the rings, (s)he is often taken aback, and can't believe that it is the "real deal".  No stickers, folks!  The way we see Saturn in the eyepiece may be far pale compared to those of the Voyager Mission pictures from decades ago, yet it still can attract at a mean distance of about 900 million miles away.
See Saturn close up, rising in the late-evening sky this week in image one, while the second image shows a zoom-in of about 1000x to show the rings and their divisions a little more clearly.  The link to kick off this entry shows a much closer image on that webpage.

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

Detailed

Saturn's rings are made up of billions to trillions of icy particles, along with some dust and "other chemicals" (not specifically mentioned from the source I used).  For size, the particles range from a spec of sand, to as big as a small house.  All together, they orbit Saturn, although to us, they look as if to be solid rings.  At the distance that we see Saturn mentioned earlier, it is of no surprise that at their size, there must be so many particles!
   (H)ydrogen and (he)lium make up Saturn's outer atmosphere, at a ratio of 96/3; minus trace amounts of other gases including ammonia and methane, those two are most often talked about.  If the H/HE mentions sound familiar, they are also the main gases that make up our Sun, although the proportion difference is much smaller.
Much like the bands that we see on Saturn's gas neighbor Jupiter, Saturn's are made up of cloud layers, although fainter.  To learn more about the cloud characteristics, check out this helpful link:
http://lasp.colorado.edu/education/outerplanets/giantplanets_atmospheres.php
What is most impressive about the rings of Saturn now, is that how much of them we can see, being another reason for image two's high magnification.  Since we are viewing Saturn straight towards its mid-northern latitudes as opposed to the equator, we see much more of the curve of the rings going around the disc.  Just a few years ago, we were looking at Saturn towards its equator, meaning that we saw the rings "edge-on"; they were hardly visible at all for about 12-14 months, yet have improved since.  The edge-on cycle happens twice per revolution for Saturn, which lasts about 29.5 Earth-years.  The change of angle when viewing the planet, is a combination of Saturn's revolving and ours, with the orbits of both planets not being in the exact same plane.  If they were even more off, we would be viewing Saturn's poles; such would give excellent ring views, yet only seeing one hemisphere at a time, for some years.
   Saturn has 62 Moons with confirmed orbits as of the count about a year ago.  That is, most are captured asteroids with perhaps a few not yet confirmed as a result of orbits with extreme inclinations. We only see 5 of them easily--sometimes 6, for if a bigger field is used than I show this time.  Enjoy the view, as Saturn rises about four minutes earlier each evening.  As Mars did earlier this month, Saturn reaches opposition in April, appearing a little brighter than it does now.

Venus' dichotomy, and same azimuths

Event Date: March 28th
Time: 6:58(.55) PM (image 1: see why so odd, below), 8:00 (image 2)

Brief

Let's talk azimuth: a term that I have mentioned a few times so far since starting the blog.  "Az" a reminder, this term refers to the relation of a star or planet to the horizon, and changes by the split-second if keeping precise values.  If we base azimuth values by the hour, the change is even more dramatic; particularly for some that transit high in the sky.  This is why if two viewers in two time zones are on the phone with each other, using their altitude-azimuth telescopes, they have struggles when looking at the same part of the sky to find a star or planet.  The reason for any confusion among the two is simple: A person in New York for example, sees a star beginning to set in the west, while someone in California sees it higher in the sky, looking south.  It is also possible to see two bright objects at the nearly-exact same azimuth: Venus and Jupiter, at the time above, as seen from our location.  Viewers at other latitudes of this longitude see them close to the same azimuth as well, although at some of them too far south, Jupiter will have already be set.

Detailed

Since I was busy marveling at the pretty Pleiades star cluster over the last entry, I failed to talk more about Venus' greatest elongation from the Sun on the 26th.  Despite that, we will see Venus very close to the same elongation over the next few days, and still very high in the sky for the next few weeks.  Also, Venus reaches dichotomy tomorrow universal time (7 hours ahead of Pacific Daylight).  This link does a good job for showing Venus' phases, including those for when it becomes easily visible as a morning target in the early Summer.  http://www.curtrenz.com/venus08.html
Dichotomy is when the planet appears half lit.  With low magnifications this seems true.  However, with high magnification, we may see it very slightly more than that.  For some times, dichotomy doesn't happen until a week after greatest elongation.  This is not an error in calculation however; it is "inherent fuzziness" of the terminator on Venus' clouds, which are very thick and cover the entire surface;
The Schröter effect is one way to learn more about this, after the namesake German astronomer.

The first image refers back to the brief section, showing Jupiter and Venus at exactly the same azimuth; see Jupiter lower down, by 12.7º.

The second image shows Venus at 50% illuminated, very close to dichotomy, shown an hour later. Although the software cannot show the most realistic of images, including the Schröter effect, it does so enough to illustrate what the effect is talking about.  The magnification of Venus in that image is about 1,000x, to show a little more clearly.

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

Pleiades up close...and car-talk(!)

Event Date: March 27th
Time: 8:30 PM

Brief

   I showed the Pleiades star cluster in yesterday's entry, yet only magnified it enough to see with a 9º binocular field.  After all, I wanted to include Venus and the Moon as well, which made a triangle shape with the cluster within that same field.  The cluster, when looked at either with binoculars or the eyes alone, has a triangle or "wedge" shape to it.  As mentioned yesterday also, some viewers who have never seen the cluster with the eye alone, mistake it with the Little Dipper asterism; I elaborated on how this mistake can be avoided by knowing where the Little Dipper is in the sky.  See yesterday's detailed section for more on that.  For now, I will show a telescopic field of view of 2º for the Pleiades, and include a little more information about it; see the image below the detail.

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

Detailed

   Let's get this section of the entry off to a fun note:  First of all, do you own a Subaru for your road journeys?  If so, have you ever paid attention to the logo?  This link shows several variations of it:
http://www.google.com/search?q=subaru+logo&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=pRdAT5adNMLfiALUloWtAQ&ved=0CD4QsAQ&biw=836&bih=436
Whether you own one, lease one, or just pass them while walking a parking lot, you may have noticed that the logo is inspired by the Pleiades.  Subaru means unite, and if we think of the Seven Sisters story for the Pleiades, the clustering of them shows true unity!  As for the cluster itself, it is an  open star cluster as opposed to a globular cluster.  Open clusters contain stars which are loosely bound by gravity, while globulars' stars are tightly bound.  In each case, the stars come from the same molecular cloud.  In the case of the Pleiades, the stars are very hot and luminous, while also quite young: the last 100 million years.
http://en.wikipedia.org/wiki/Pleiades shows many more images of the Pleiades, as well as information.  The cluster is slightly further north on our celestial dome than the Sun, at 24º north.
Why does this matter?  If you recall what I talked about yesterday with the Moon's orbit having ecliptic latitude extremes of 5 1/2º, with two nodes, that is why.  As further elaboration, I will dive back into the Moon's orbit topic tomorrow.  For now, think about what the orbit means for the Pleiades and the Moon, in regards to angular separation between the two...or lack thereof at times!  I will go into more detail about that as the Moon's orbit's main characteristic puts the Moon in slightly different parts of the sky.

Little Dipper, and Pleiades near Solar System bodies.

Event Date: March 26th
Time: 8:00 PM

Brief

This evening, we continue looking west as we did yesterday.  I forwarded the clock a bit to show a darker sky.  The reason for this is not just to show the waxing crescent Moon, which is now seen near Venus instead of Jupiter; let's show the famous Pleiades star cluster as well!  This is the brightest and--unarguably because of its appearance in optical aid--the "prettiest" star cluster in the sky.  With the eye alone, some see the six (or more?) visible stars as a wedge, or pizza slice.  Others however, with little astronomy viewing practice, mistake it as the Little Dipper.  Read more about that below, and afterwards, enjoy the image I included of the Pleiades magnified in binoculars with the Moon and Venus.  Preceding that one, is one zoomed out including the ecliptic and the Moon's orbit, which I also talk about next.

Detailed

Although I haven't talked about the Little Dipper along with its "big Brother" Dipper (in size anyway!), the shape is similar as shown in the images for this link above, and I will show it tomorrow.  Since the star Polaris, which I mentioned a few days ago, marks the end of the Dipper's handle and the bear's stretched out tail, that acts as a reminder that the dipper is very close to the northern celestial pole.  The Pleiades however, is much closer to the celestial equator in comparison, and will never appear as far north as either Dipper.
   As for the Moon's position, some viewers on the other side of the world saw it in line with both Venus and Jupiter.  I included its orbit in the image, along with the ecliptic to show the Moon's path over the next few days.  I do this, since the inclination of the Moon's orbit is about 5 1/2º at its extremes.  As shown in the first image, there is an arrow marking the descending node: this is one of two nodes, where the Moon switches in ecliptic latitude, which I mentioned briefly in the "equinox" entry back on the 19th. 
    I will talk more about the nodes later in the year, when we find out why they are so significant.  This last image brings us back to the Little Dipper's position in the sky, almost directly north.  Observe the stick figure, which shows the position of the handle in relation to the cup.  Being a circumpolar asterism, long nights during the winter, late fall and early spring, give us a chance to see the Little Dipper's dim stars make a revolution around the north Axis.  Polaris, marking the tail, makes the tightest revolution.

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

Venus, Jupiter & the Moon: 3 brightest targets

Event Date: March 25th
Time: 7:25(.51) PM *official Sunset time  

Brief

Venus is the dominating "star" in the western sky for the next two months, and will become even more so for two reasons during that time:
(1) Jupiter, paired nicely with the waxing crescent Moon this evening as shown in image 1, is sinking rapidly into atmospheric pollution and the glare of the Sun.

Add caption

Jupiter will eventually go behind the Sun and out of our sight.  When the two are at the same right ascension, that is called conjunction. 

(reason #2)
Venus will continue to brighten--although not too noticeably by looking at it--as it becomes closer to us in orbit.  As an inner planet, Venus is catching up with Earth, the same way that we catch up with planets Mars through Neptune.  As a result of the difference in distance between Venus' two types of conjunction, inferior and superior, we have seen it already increase in angular size, and will continue to further.  As it does so, the extra disc-area of reflected Sunlight to our eyes makes it seem brighter.  I will talk about that in detail more tomorrow, yet to follow, here is some other information about Venus this evening.

Detailed

Since December, Venus has become slightly brighter each evening, and easier to see above the horizon, becoming slightly more north of the Sun each day.  The planet is a little over 44º in altitude, almost exactly halfway between the horizon and zenith.  As a result, if a viewer gets a telescope on Venus during this hour, especially if there is little of no wind, Venus could look very still.  That is, it would be without the "ripple" that we see when close to the horizon, within atmospheric pollution.  Venus is only two days away greatest elongation (g.e.), for when it is at its furthest from the Sun in separation.  Since it reached perihelion a little less than a week ago, this g.e. will not have it quite as separated as when such happens at aphelion-- its furthest distance from the Sun in orbit; the aphelion happens in about 3 1/2 months, when Venus starts to re-emerge as a morning target in the early summer sky.  Sticking with the evening showing for now, Venus' difference in northern latitude (declination) with the Sun is also contributing to the greatest "gap" in set times for both for the remainder of the month: the Sun at 7:25 PST, and Venus, a late 11:20, meaning 3 hours, 55 minutes.  The largest gap is a minute extra, occurring during the month's last days and into the first few of April.  During this time, Venus continues to move far enough north on the celestial dome to stay above the horizon, and long enough to maintain the maximum gap.  Eventually, as it starts to move back towards the Sun, while the Sun continues to move north on our celestial dome, the gap will shrink gradually, yet rapidly by late May and early June.
   Image 2, representing much of what I said here in this section, includes the Moon and planets' orbits, along with the ecliptic and celestial equator:

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

These latter two guidelines were introduced when I showed the Sun at equinox last week, and the angle they make with each other will continue to change more and more quickly with each passing week.  Finally, I included a grid for altitude, representing Venus being as high above the horizon as it is for the time of Sunset.  For our altitude, it is about as high as we ever see it, with the favorable geometry at this time of year in the western sky.  All three bodies are still well-north of the Sun, although that changes at various dates for both: first for the Moon, then Jupiter, and then as mentioned, for Venus.

Scorpious, Libra and "Claw" Stars

Event Date: March 24th
Time: 5:30 AM

Brief

   Finding recognizable constellations and asterisms is a fun activity; whether someone is just becoming introduced to astronomy, or has followed it for years and is suddenly starting to recognize shapes.  Besides the Big Dipper for asterism and Leo for constellations, there is another one that caught attention long ago: Scorpious!  Looking at the stick figure below, the name fits the scorpion shape well.




Detailed

The tail, a somewhat-recognizable head, and two stars stars seen further west (right), one time represented the pinchers of the Scorpion.  Those two stars, Zubeneschhamali and Zubenelgenubi maintain their names despite the switch, as northern claw and southern claw respectively.  Although they are no longer part of the Scorpion, they are the brightest of bordering Libra the Scales.
Why were they switched?  Find out here, among other info.  For example, according to astronomical history, Libra was part of another bordering constellation before Scorpious!  Can you guess which before reading?
http://www.buzzle.com/articles/libra-constellation.html

The first image showed with the stick figure and labeled claw stars, while for the second, only the stars show, so a viewer can attempt to visualize the scorpion.  Can you?

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

The time for both images is the same.  Therefore, just look at the same part of the sky, just slightly east of south for when the constellation is almost at its highest in the sky.  This is where the Sun is located in the late fall, when seen low, and weather starts to get colder, with shorter days in the northern hemisphere.  In the southern hemisphere, this constellation is usually seen during the night very high in the sky, and where the Sun is in late spring.

celestial poles & axis precession

Event Date: March 23rd
Time: 9:00 PM

Brief

   I will continue from yesterday's entry with the Big Dipper, and mention another reason why it is significant, besides being a distinguishable asterism: two of its stars act as excellent path finders.  Such stars are also defined as "hoppers", meaning that a path from one to another leads to a hop to another, or a deep-sky object.  In this case, let us look at the stars Merak and Dubhe.  In that order, a line drawn straight through them leads nearly to both our north celestial pole, and--visibly to our eyes--the star Polaris.  The name says it all, as this is the brightest star within even a wide binocular view of the pole.  At precisely 2nd magnitude, this star with clear dark skies above open seas was--and still can be--a great target for mariners to use to navigate.  After all, 4-500 years ago (and I mean this jokingly of course), GPS wasn't what it is today! 
   For the first image shown below, imagine a line between the aforementioned Dipper stars, and the straight path that almost hits Polaris.  The celestial pole is marked also, although not quite as in line with the stars.  I also included the celestial grid to show how it is 20º incremented towards the pole.  As a reminder, the pole's altitude above the horizon, as seen from any part of the northern hemisphere, is the same as the latitude of viewing.  Therefore, our pole from select location is slightly less than 38º high.

Detailed

Polaris is about 0.7º away from the celestial pole, although a certain characteristic of the Earth's axis will have it seen a little closer to the pole each year until the end of the century: precession.
A rapid, yet interesting animation can be seen at this link http://en.wikipedia.org/wiki/Precession which shows our Earth as if it was spinning very similarly to a top, in that struggling manner before [the top] is about to fall and stop.  This animation shows that motion as continuous, as it will be over the next countless number of years.  As a result of precession, Polaris isn't always our brightest star closest to the pole; the cycle is close to 26,000 years, so alot changes gradually over that long span.  The animation however, bends that duration to one precession per second, or over 800 billion times faster than real time!  Of course, that is to give us the concept of the top-like motion, so understandable for that reason.
   Getting back to Polaris, it will seem to creep closer to the pole and expected to get as close to it this week during the year 2100.  For years after that, look at the precession cycle circle in the upcoming images, for what other unaided eye stars will be close to the pole, before the return of Polaris. 
   Unfortunately for southern hemisphere viewers, their "pole" star for now and over the last several centuries is much dimmer, and wasn't too helpful for navigators over the last several hundred years.
These next two images show both the north and south celestial pole and their precession cycle circles:  first the north, then the south.  For both, the stars vary in magnitude and separation from the circle, while a few of them (such as Vega) are brighter by far, than Polaris.  Notice for the southern hemisphere, that although as far as 8º from the circle, there is a bright enough star that will be that close for a few thousand years: Canopus, as our second brightest star as seen from Earth, in apparent magnitude.  This star can be seen briefly above the horizon in the southern states, and seen longer if viewing from as far south as Mexico and further.  After the star Sirius Sirius (magnitude -1.5), another southern hemisphere star closer to the equator, Canopus appears a little dimmer at magnitude -0.7, yet only slightly noticeable, when both are seen high enough in the sky.

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

  

Ursa Major including the Big Dipper

Event Date: March 22nd
Time: 9:00 PM

Brief

   Yesterday, I brought up the talk of asterisms when showing the Sickle of Leo: stars that make a recognizable shape or figure within a constellation.  I also threw out a teaser for today's entry, regarding a much more recognizable asterism in comparison to the "backwards question mark", that represents Sickle as the Lion's mane.  For this evening, the Big Dipper is my asterism of discussion, and perhaps arguably, the most popular in the sky.  As a challenge for some viewers to imagine, the Dipper makes up the body and stretched tail of Ursa Major-- the Big Bear.  Both the Dipper alone and with the stick figure of the Bear, are shown in the images for this entry in that order, at the end of this section.  As it can be seen, the handle and "cup" portions of the Dipper can be easily seen with only seven stars.  These stars came from the same molecular cloud and therefore, all about the same magnitude and within a small range of distance from the Sun; small in comparison to stars of other asterisms, anyway.  The stars are labeled in the image, and range in magnitude from 1.8 for Alkaid, to 3.3 for Megrez.

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

Detailed

   The Big Dipper, which is much easier to see than the rest of the stars which make up Ursa Major, has been a favorite of northern-hemisphere viewers for a second reason, besides the configuration of the stars: it is seen as circumpolar.  As the animation in this final link shows, the stars are far north near the axis.  As seen from most northern latitudes, the Dipper stars are above the horizon 24 hours, 7 days a week.  For northern latitudes close to the equator, they are above the horizon most hours, although perhaps too close to it, to see easily if any obstruction.  From the southern hemisphere, depending on how far south a person views from, the Dipper is seen either as long as 12 hours a night (nearest to the equator where nights barely are that long) to not at all (the south pole).
  As we talk more about latitude as this series progresses, I will consistently put the celestial grid in the image, as I have above; it can be seen in image 1 this evening, and as shown, least-northern Alkaid is the only star that just barely sinks below the horizon...albeit less than three hours.  Any star seen at our latitude that is of declination 53º N or greater, is circumpolar.  This is figured by a simple calculation: 90º minus our latitude (about 38º).  Since we are just a bit south of the 38º mark (37º 49' 09"), that translates exactly to 52º 10' 51") for the difference.  Stars at this declination would graze the horizon.  Therefore, if about a degree further north, with both an obstruction-free horizon and from a high elevation, the stars of the Dipper bright enough to be visible through atmospheric pollution, and perhaps be seen with the eye alone.
Enjoy the Dipper, and if you are a night owl, watch it curve high in the sky directly north, before starting come low again very gradually.

Mars bright, and in retrograde

                             
Event Date: March 21st
Time: 7:30 PM

Brief

   The planet Mars, often referred to as the "red" planet with its distinguishable color from the others, is still close enough to Earth in orbit for us to notice this color with the eye alone.  Using optical aid makes Mars easier to see, although it is best to wait until the planet is high enough above the horizon.  Atmospheric pollution and any lingering haze, take away from Mars' natural appearance.  When first viewing the planet after Sunset, it is more than 25º in altitude above the horizon; it is high enough that its color should be noticeable with little interference.  With Mars' surface being covered with rust, less commonly known to some people as iron-oxide, we may see slight variances in the color, based on the varying depths of rust.  Find out more with this reading:
http://www.universetoday.com/22580/why-is-mars-red/

Detailed

   As shown in the image, I have plotted a six-month celestial path of Mars, as we have approached it in our orbit.  A celestial path shows a planet's position relative to the background stars.  For this one, it is incremented in 10-day periods with circular markers.  As we caught up with Mars in orbit, it was similar to riding a train and passing a slower one on parallel tracks.  Just as that train would appear to move backwards, Mars' further distance from the Sun, hence longer orbital period, makes it appear to move backwards against the stars: east to west instead of direct (prograde) motion, which is movement west to east.  This backwards display is called retrograde motion, and it is sometimes mentioned also in weather reports: when tracking storm patterns, clouds can be seen on satellite images moving in such a manner.
  Getting back to astronomy, the path acts as a visual, and where the change of direction is shown, that is where Mars appeared stationary to us for a short time. 
Why is it called stationary?  If we were to view it in a telescope, the visible stars around it would appear to be the same separation for several hours during the night.  As the markers indicate also, Mars started to apparently move faster in retrograde, with the fastest being very close to where we passed it in our orbit.  It is on this evening, that Mars rose about the time that the Sun set, being opposite the Sun in the sky.  Therefore, this is called opposition, with an elongation of 180º with the Sun.  Since then, the now-obstuse elongation angle between the two has started to shrink, and the rate of retrograde will further slow down for the next few weeks.  It began in late January of this year, and ends in mid-April for a duration of a little over 2 1/2 months. 
   I will talk about retrograde periods for the outer planets as well when they happen, which--partly because they are further away--are longer than Mars'.  For now, following this text is the view that we have of Mars during civil twilight with the path included.  Search the east-southeastern sky with binoculars or a telescope if you don't see it right away.  Within most binocular fields, Regulus, the brightest star as seen from Earth is within the constellation of Leo, the Lion, is less than 8º away.  Between now and when we next see Mars as stationary, it will seemingly creep up on Regulus, putting the two within common binocular viewing fields.  The 'stick' figure for Leo, being one of the most recognizable among our constellations, shows, with what many think of as a backwards question-mark shape (?) representing his mane.  This is called the Sickle of Leo, and is an asterism: a recognizable part of a constellation.
   What other asterisms are you familiar with?  There is a very recognizable one in the northeast that I will talk about tomorrow!

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

orbit extremes & Venus apparition

                        
Event date: March 20th
Time: 6:05 (PM)

Brief

   There will be several times that I will use the term astronomical unit (a.u.) to indicate the distance of planets from the Sun and each other.  An a.u. is the average, or mean distance between the Earth and Sun.  To find this distance, which is approximately 93 million (mi)les, the distances of the Earth from the Sun at perihelion in January, and aphelion in July are averaged.  The distance between the two bodies are 91,402,640 mi at perihelion and 94,509,460 mi at aphelion.  The table included for the mean distance link above has these units in kilometers (km) instead of miles, so use whichever system suits you best.  As a result of ellipse-shaped orbits with the Sun not centered, the other planets of our solar systems have mean distances to calculate also; they can be found using that same link by scrolling up and down from one table to the next on the website.                     
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Detailed

   We will use Venus as example for talking planet-Sun distance, since it reaches perihelion today at the time listed of 06:05 PM, PDT.  Venus at this moment, is about 66,784,500 million mi from the Sun.  If you have noticed a very bright "star" high in the west just after Sunset over the last several weeks, that is Venus!  Reaching perihelion hardly effects its apparent magnitude, which is how bright we see it from Earth.  Instead, as Venus comes closer to us every day during this time of its cycle, we are seeing more lit area of the planet.  The sulfuric acid clouds covering Venus' entire surface reflect alot of Sunlight, while the difference of Venus in distance and therefore angular size, changes dramatically during the periods that we see it on either side of the Sun. 
The first image shows Venus where it is in orbit, zoomed out, while the second shows it more zoomed in.

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

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

   When looking at image 1, the dim/thin part of the orbit indicates the curve further from our line of sight, while the bright/thick part is where the planet is when closer to us.  Right now, Venus is only about a week away from what is known as greatest elongation, when it will reach its greatest angular separation from the Sun.  It is important to remember, that this should not be confused with greatest distance from the Sun, which is its aphelion, mentioned earlier.  Being just short of 46º in separation, that is about 1 1/2º from maximum separation from the Sun close to, or at aphelion.  In short, when at perihelion, the angular separation is not much different than when at aphelion.  However, because Venus is currently further north on our celestial dome than our Sun, we still get to see the planet for almost 4 hours after the Sun each evening, for the rest of the month.  The celestial latitude difference between the two, which I defined in yesterday's entry as declination, reached its peak last week, and now are 19º different.  When Venus has a greatest elongation east of the Sun during the weeks of between mid-February and early March for the northern hemisphere, this difference makes sense; just as we notice our Sun rising north and setting later at faster rates than other times of year.  How does that relate?  Yesterday I introduced the ecliptic and celestial equator for the equinox.  Now that the Sun is past their intersection, watch the path it makes on the ecliptic over the next few weeks, relative to the celestial equator; Venus has moved along this section of ecliptic already, east of the Sun.

March Equinox

                             
event date: March 19th
time: 10:15(.28) PM

Brief

When we think of the first day of spring, people in the northern hemisphere are aware of it happening in late March.  Just the opposite, those residing in the southern hemisphere think of it happening in late September.  There are other terms more commonly used in astronomy for these days: equinox, vernal and autumnal. The vernal equinox refers to spring beginning, while autumnal refers to autumn or "fall" beginning.  As my title displays, to avoid seasonal confusion, the equinoxes are also based on the month of the calendar: March or September.  These two links give more detail, answering a popular question: are day and night exactly the same length on the equinox dates?  If not, is there a term for that too?  The answers are no and yes respectively, as well as where the word is derived from.  Images and other helpful visuals are presented.
http://en.wikipedia.org/wiki/Equinox
http://www.timeanddate.com/calendar/march-equinox.html

As others may, I like to consider the moment of the vernal equinox for the northern hemisphere as the marking of the *astronomical new year, based on the Sun's position in the sky along its annual path: the ecliptic.  To find out more about that, read the detailed section to follow.
*From this point forward, the detailed section will often elaborate on the brief section, therefore, my only mentioning it here as the first entry.
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Detailed

   The following two images from my version of Starry Night Pro-Plus software are perhaps more abstract than those shown from the links in the brief, yet can still make sense with some basic lessons in astronomy.  Remembering that Earth's axis tilt of very close to 23.5º, leads to my showing two different sets of grids offset in the first image: red and green.  If there was no tilt at all, a second grid would not be necessary; the Sun would rise at the same azimuth points relative to east and west, and transit at the same altitude every day if standing at the same terrestrial latitude.  This would lead to us becoming weather-bored because of the lack of seasons; I would become so, anyway!
   Looking at image one, we see four labeled key gridlines: the celestial equator, ecliptic, celestial meridian and ecliptic meridian.  **more text to follow image.

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

The celestial equator represents our equator on Earth projected into space, as is the case with our global latitude and longitude coordinates.  The ecliptic equator, or simply known as the ecliptic, marks the path of the Sun in our sky as a result of the Earth's axis tilt.  The extreme points of the ecliptic north and south of the celestial equator, equal that of the Earth's tilt, at 23.5º.  The grid is really only included this time, to show how much more offset it would be if we had a greater axial tilt.  Think of outer [solar system] planet Uranus in comparison, with its near-90º tilt!
The celestial meridian marks very closely, where the Sun is at the equinox in celestial longitude: zero hours (think 24 hour, or military time on a watch).  Longitude is measured in (h)ours/(m)inutes/(s)econds, and I will show longitude measurements using this notation.  It is also known as right ascension, or r.a. for short.  The ecliptic meridian plays more of a role for measuring the exact time of the equinox; measured in degrees(º)/arc-minutes(')/arc-seconds(") instead, when the Sun is exactly at the 0º 0' 0" mark for ecliptic longitude.  *If an astronomical new year is to exist, this is it, in my opinion!  The ecliptic meridian also marks 180º 0' 0", which is where the Sun is at the time of our autumnal equinox,  and vernal for the southern hemisphere.  The latitude lines for both the celestial and ecliptic grids, are known as declination and ecliptic latitude respectively.  I will talk about both of those more for planets, deep sky targets and the Moon, for future entries.
   Also in image 1, the horizon is hidden, as if we are looking through the ground beneath our feet, to see the Sun below the horizon at this late-evening hour.  The second image shows the Sun zoomed in to a field of view (FOV) of 1º to show more closely how it is centered on certain gridlines.

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

 It also shows how these lines converge towards each other in this part of the sky, very close to the Sun at equinox.
   Finally, the time listed in the images--10:15.28 PM Pacific Daylight Time--indicates that of the equinox from our viewing location, as opposed to if a viewer was standing exactly in the center of the Earth's core, since this is impossible.  As the table from the Wikipedia link shows above, the equinox time is listed about a minute earlier, based on the Earth-center perspective.  Depending on which week of the year, most entries here will use Pacific standard or daylight time.  The former being 8 hours behind Universal Time (UT--Also known as Greenwich Mean Time (GMT)) and the latter 7 hours behind UT.  When clicking on this time link, between the second Sunday in March and first Sunday in November of the same calendar year, we will notice that when comparing the hour difference for Pacific time zone, there is no daylight savings change for UT.
So, happy March equinox, and astronomical new year. :-)

Introduction

   Hello, fans of the cosmos-- or someday soon perhaps!  Welcome to my astronomy journal, now about to be in blog form after 5 years.  On that note, if you want to read anything from my non-blogged archive, feel welcome to contact.

   The entries will include a daily series of astronomical facts, figures, bits, trivial stuff, and--most amusingly--alot of things that you may not give the slightest darn about, yet find fascinating and intriguing anyway! 
important note: keeping the aforementioned in mind, and since I am a novice when it comes to blogging, most entries will be divided into two sections:

brief
if you are--for some strange reason--in a rush out the door, yet care enough to give my words a little attention.

detailed
given the length of this intro, if you even finish reading it, you may want to ignore this section; unless perhaps, you are extremely curious in what I have to write about, and obsessively compelled to check it out.
  -------
 I will start the series this coming Monday, March 19th; more on why that is later, in entry #1.  Chabot Space & Science Center (CSSC) where I spend more time than I can sometimes keep track of, will be the location for which my software image coordinates are based.  Unless otherwise noted, CSSC will be the viewing point of all of these images and journal references to such, using the coordinates of the observatory plaza there; more exactly, the center of Compass Rose on our plaza, at 37º 49' 09" North (37.81926º), and 122º 10' 54" West (122.18171º).  Is that exact enough for you!?  If you don't believe me, map it, zoom in a bit more, and find that you either (a) feel silly for having just wasted your time by not believing me, (b) found out how cool it is too see us from above...or both! 
   Getting back on topic, sometimes the info given can apply to surrounding locations anywhere in Oakland proper, or more rarely, the entire Bay Area.  However, a few highlights will, or might, require one to be at Chabot's observatory plaza only. 

   Throughout these journals, I will also include images from Starry Night® (SN) software, giving proper credit naturally, in each journal.  Using SN pro-plus 6, including regular updates, I will "paste" at least one image per entry.  Sometimes, I will include an image that looks like the real, night sky.  Other times, I will alter them to illustrate and point out what I am trying to put my focus [of attention] on.  This software may not be perfect, but it does have some near-realistic images, thanks to good resolution and much more that was put into it by the creators, engineers, techies, etc.  I will also include alot of info such as time, celestial coordinates, number values for measurements, and much more.

   Okay, that's enough yapping with this long-winded intro.  Let's start the journals for a blog that I perhaps should have started 5 years ago, and see how far I get with them!  Enjoy, happy reading and viewing...weather permitting, of course. :-)