Tuesday, April 8, 2014

April skies: Mars and a visit from the ISS

It's April - spring is in the air, and we're guaranteed at least a few more snow storms before summer finally graces us with it's ephemeral presence.  The upshot of all this is that, although the nights are getting shorter, they're becoming far more tolerable for stargazing.

This evening I stepped outside around 9pm to enjoy some beautiful skies.  Orion is now in the western sky and will be leaving us in another month or so.  To the north of Orion, Taurus and the Pleiades round out the trio of fading winter constellations.  Look for the "V" of Taurus with a bright red star - Aldebaran, the eye of the Bull - on one end.  The Pleiades are often described as looking like a faint, slightly hazy, tiny big dipper.  High in the western sky, Jupiter still reigns as king of the skies, but Mars is currently a worthy competitor.

Look to the eastern skies and you'll find two bright red stars - one is Arcturus, part of the obscure constellation Bootes, and the other is the planet Mars.  Mars is the brighter of the two and further to the south.  In my astronomy classes I teach my students to recognize Arcturus by using the phrase "Arc to Arcturus", which means to find the handle of the big dipper and draw an imaginary arc that traces the handle down to Arcturus.  Currently, if you continue the arc past Arcturus, you'll wind up in the vicinity of Mars.  The bright blue-white star below Mars is Spica.

Mars usually isn't all that spectacular, but currently Mars is unusually close to Earth, in a position called "opposition", where Earth and Mars are on the same side of the Sun.  Today marked the closest approach of Mars to Earth in two years.  The next opposition will occur in May of 2016.  Looking at Mars through my 4" telescope, I observed a small red disk.  The fact is, Mars is small - about half the size of Earth, so you need a larger telescope than I have in my back yard to see anything terribly interesting, like polar ice caps (or canals).  I would suggest checking Mars out with the Gunnison Valley Observatory's 30" telescope when they open in June - of course Mars won't be quite as close then, but it may still be worth looking at.
Relative positions of Earth and Mars around the Sun with positions and dates of opposition given.  Diameters are given in arcseconds - one arcsecond is 1/3600th of a degree.  One degree is the apparent width of your thumb at arms length, so Mars' current angular size of 13.9 arcseconds is still very, very small.
While I was outside, I had the pleasure and good timing to catch a sighting of the International Space Station as it passed overhead.  Observe the stars for any length of time and you're likely to see some satellites - they look like moving stars - they move about the speed of a high flying airplane, but they don't blink.  The ISS is quite the sight to see because it is exceptionally bright - brighter than most stars in the sky.  You don't have to rely on luck to see the ISS - just go to http://spotthestation.nasa.gov/ and look up upcoming sightings in your location.  If you're in Gunnison, the space station will be visible tomorrow, April 9th at 8:13 and 9:50 PM, as well as Thursday at 9:01 PM.  Look to the north for all of these sightings.  There are also additional opportunities to spot the ISS almost every evening for the next two weeks.

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