Tuesday, February 23 2010 @ 11:13 am EST
Contributed by: dgrosvold
Orion the Hunter will be at its highest point in the evening sky this month. By late March, you will notice him sliding back down toward the western horizon, just a bit lower at the same time each successive evening. Orange super-giant Betelgeuse (BEE-tel-joos) at Orion's upper left shoulder forms one apex of the Winter Triangle, with Procyon (PRO-see-yon) and blue-white Sirius forming the other two. Procyon and Sirius are the brightest stars in the two constellations that represent Orion’s faithful hunting dogs, Canis Minor, and Canis Major, respectively.
On the Apparent Magnitude scale, the higher the number, the dimmer the object, so Procyon, which is Magnitude 0.45, is dimmer than Sirius, at Magnitude -1.45. Sirius is considered the brightest star in the night sky. Venus is much brighter, at Mag -3.80.
The International Space Station (ISS) and Iridium Flares can both be brighter than Sirius, and sometimes even brighter than Venus. This week, the ISS will be almost as bright as Venus on Wednesday morning (Mag -2.9), when it passes overhead at 6:00 AM, swinging from an altitude of 20° in the WNW, up to about 43° in the SW and then back down to 10° in the SSE.
There will be four Iridium Flares visible this week, on Thursday and Friday evenings, and also Friday and Saturday mornings. These flares will be approximately Mag -2.0, so they will be brighter than Sirius in the evening and pre-dawn skies. Look for them in the south at 6:58 PM on Feb 25 (Iridium 66), and 6:52 PM on Feb 26th (Iridium 21), at an altitude of 48°. The flares will also be visible in the south at 5:35 AM on Feb 26th (Iridium 18), and 5:29 AM on Feb 27th (Iridium 39), this time at an altitude of 39° above the horizon.
By the 25th, the Moon passes within 5° of Mars, and by the 27th the bright nearly full Moon will be only 4° below Regulus, the front shoulder of Leo. Remember, the width of your index finger held at arm’s length is about 1.5°, so three fingers would be about 4.5°.
Fiery Mars is past opposition now, so it won’t be as bright as it was last month, but it’s still a great target in a small telescope. Mars rides high in the sky this week, in a line below the twins of Gemini, about halfway between them and M44, the Beehive Cluster. Look for Mars in the eastern sky at 8:00 PM.
Saturn will be rising in the East just before 8:00 PM on the 27th. You can catch Saturn’s largest moon, Titan at about the 1:30 position in a pair of binoculars or a small telescope anytime after 8:30 PM. Remember that most telescopes either invert the image or mirror it, so you might have to look at the 7:30 or 10:30 position in your scope, unless you have an erect-image prism in the optical train.
The bright asteroid Vesta, is just past opposition and still at magnitude 6.1. Vesa continues its travels across the Sickle of Leo, as shown in the last image. You should be able to spot it in binoculars.