Night 1: Mars and Saturn

002:Mars
003:Saturn
004 Titan
005:Rhea

.....So far, I have had two successful observing nights, taking me up to nineteen objects on my list.  I'll go through these objects by type of object, because that makes the most sense to me at this moment.

.....The first two things I looked at in the night sky were the planets Saturn and Mars, low in the west.  I started with Mars because Mars was closer to the western horizon (just above the trees for me) and close to being lost.

.....Mars is currently low in the west, and setting very shortly after dark.  Since I want to see what I can get over the course of one year, Mars had to be observed now.  The problem comes from Mars being as close to the Earth as it is.  Let me explain.  Mars is the next planet farther out from the Sun, and so it moves in its orbit a little more slowly than the Earth does.  Saturn is much farther out, and moves much more slowly.  That means that one year after Saturn's best appearance in the sky, when the Earth has made one orbit around the Sun, Saturn has moved a little bit farther along (1/30th of the way along its orbit), and so the Earth must move a little bit father to catch up.  In the case of Mars, Mars has an orbit that takes 1.88 Earth years to complete.  When the Earth has gone once around the Sun, Mars has made a little less than half of one orbit, so Mars would then be on the other side of the Sun.  It will take almost another full year for the Earth to catch up to Mars in its orbit.


.....I have a confession to make:  I have never really been a fan of observing Mars.  Part of this might be due to Mars' habit of being visible basically every other year.  Heck, in addition to this, the relative size of Mars in the sky can change notably, due to how the position of Mars changes with respect to the Earth, and its own exceptionally elliptical orbit.  (Notably as far as looking at it in a telescope goes.  Despite the emails that still go around every August, Mars will never appear as a big red moon in the sky.)  The image below shows the orbit of Mars (red) and the orbit of the Earth (blue), to demonstrate how widely the distance between the two can change.

  ..... The two orbits can come pretty close to each other; this happened in August of 2003.  Marked on the chart was the last closest approach of the Earth to Mars, when Earth passed Mars in its orbit back in March.  Even at this closest approach, this wasn't as good as the 2003 event.  In a telescope, the image of Mars would be about 2/3rds the size at an absolute closest approach.  Mars as it appears today is almost a third the apparent size that it had back in March.

Don't count on this good a view

.....On a good night, the facing ice cap of Mars may be visible, as well as some darker/lighter areas on the planet.  These darker/lighter areas have lead to problems in the past.  This is a best-case scenario, though.  The thin atmosphere of Mars can sustain dust storms that can last several weeks, and the thinness of the atmosphere means that these storms can cover all of Mars.  My view of Mars was as a distinctly red dot.  That's it.  (That is probably simply due to how low Mars was in the sky.)

.....Saturn showed a better view.  Saturn is one of the few things in the sky that actually looks as one would expect it look.  Most people, seeing beautiful photos of nebulae or galaxies are quite disappointed seeing them in the telescope.  Cameras can be left open building and building up light in a way the eye cannot.  Saturn, however, clearly shows its amazing and beautiful rings.  Also visible are some of its brightest moons.  On the sketch that I made, I went back after the fact to identify which moons I had seen.  There must have been some thin clouds that night, or perhaps it simply was not fully dark yet, because I was only able to see Saturn's two brightest moons, Titan and Rhea.  Titan has a visual magnitude of 8.50 (dimmer than what can be seen with the eye; I describe star brightnesses here), and Rhea has a brightness of 9.89.  

.....I have omitted the decimal point from the labels on my sketch for hopefully obvious reasons.  I can usually see down to about a visual magnitude of 12 or so in my telescope, on a good night, so Tethys (m = 10.39), Dione (m = 10.59), and even Enceladus (m= 11.89) should have been doable.  I'll try and add those to the list next year.  Saturn will be a morning star starting in January, moving slowly back into view in the evenings.


.....What are the other planets doing right now?  Until November, Venus will be a morning star.  I could get up before dawn in order to see that, but I think I'll focus on the sky as it is seen in the evening ... just because that is when most people have the combined time and inclination to look at the sky.  After November, Venus will pass behind the Sun for a few months, and appear as an evening star again in May of next year.  So, there is time to see Venus as part of my "Big Year" in a more comfortable fashion.

.....Mercury is an evening star now, but Mercury is also very hard to see.  The closest planet to the Sun is also (by necessity) always close to the Sun in sky, so one needs a very good eastern/western horizon to see it.  At 9:30 PM, Mercury is about 8 degrees above the horizon.  Hold your hand out at arms length.  The four fingers of one hand, viewed across, block about 8 degrees against the sky, so when Mercury can be see, it will be pretty close to the horizon.

.....Neptune will be well placed for viewing in September; Uranus will be a bit later, in October, and Jupiter will be placed for good evening viewing by November.