By Andy Veh, for the Redoubt Reporter
We had a great summer with many sunny and warm days, probably not taking a look at the one star that was visible almost every day. That’s a good thing, because at a distance of only 94.5 million miles, it so close that it is just too bright — our sun.
Now that nighttime has increased appreciably, a lot more stars can be seen and safely viewed. They’re much farther than our sun, at distances of 50 trillion miles and more, so they appear as small and more or less faint (or bright) points of light when compared with the sun.
During late evenings last month some prominent bright stars, such as Arcturus, Vega, Deneb and Altair, were already visible. Now it’s easy to find constellations, such as the Big Dipper low in the northwest. Take the distance between the Big Dipper’s last two stars and extend it five times towards the zenith (the point straight up) and you get to Polaris, the North Star, which is a semibright star at the end of the Little Dipper’s handle. It also marks our latitude on the Kenai Peninsula at 60 degrees above the northern horizon.
Next, find the constellation Cassiopeia, in the shape of a W, on the other side of the Little Dipper, high in the northeast. High in the sky, as well, almost in the zenith, is Cygnus, the swan (it also looks like a cross). Its brightest star, Deneb, connects with two other bright stars, Vega and Altair, in the constellations Lyra, the harp, and Aquila, the eagle. Together they make up the prominent summer triangle.
Just left of that is the Great Square of Pegasus, high in the southeast. Turning to the west we can see bright red Arcturus setting, a sign that summer is over. It can also be found by following the Big Dipper’s handle’s arc.
Rising in the northeast is bright yellow Capella, a corner of Auriga’s pentagon. Throughout the night, all constellations move from east to west (of course, it is Earth rotating that gives us this illusion), so the evening western constellations set. Meanwhile, in the east, Taurus, Orion, Gemini and Cancer are rising throughout the night, telling us that winter is approaching.
It seems that the planets are trying to hide from our view — no bright planets appear currently, at least in the evening. But you might try for Neptune and Uranus, which appear relatively high in the south in Aquarius and Pisces (both are below Pegasus). A good finder chart is needed though. For example: http://www.skyandtelescope.com/wp-content/uploads/WEB_UrNep_Finders.pdf. The full moon joins them Sept. 25 and 28. That might make it easier to locate the planets, but it also makes the sky brighter around them and diminishes the contrast.
For the bright planets we have to wait until the morning, but then they come in full force. Before dawn you can see Venus, Mars and Jupiter lining up with Leo’s Regulus just above the eastern horizon. Very bright Venus can be seen during the predawn morning, with reddish and fainter Mars below it (right next to Regulus). Jupiter joins them later in the month. The crescent moon that joins them early in the month is not much of a guide because Venus itself is so bright. The accompanying diagram shows the predawn sky (the compass points are labeled, as well as the zenith, which is the point straight up).
Mercury is too close to the sun to be viewed from here. Saturn is in the constellation of Scorpius, which is very low on the horizon in Alaska. Therefore, neither of them can be observed this month.
A partial eclipse happens Sept. 13, but it’s only visible in southern Africa and Antarctica. A lunar eclipse occurs on the evening of Sept. 27, but at sunset (when, by definition, the full moon rises) it’s almost over, so the last hour of that total lunar eclipse happens too low on the horizon. Observers in the Lower 48 should see more of it because, for them, the moon rises earlier.
Andy Veh is an associate professor of physics, math and astronomy at Kenai Peninsula College.