Astronomy: The Week Ahead – Sun 08 Mar to Sat 14 Mar 2015


Sunday March 8

Due south at sunset is the constellation Canis Major and its brightest star Sirius. Sirius is the brightest star in the night sky at magnitude -1.5 and is a double star, a binary star system. The companion, Sirius B, is a white dwarf star, shining at magnitude 8.5. The brightness of the primary can make seeing the companion difficult, but you can do it in a telescope. Its separation from Sirius A changes around every 50 years, and it is now approaching its widest separation. Read up on Sirius, you’ll be amazed at what you learn, it’s a very interesting star!


Monday March 9

The constellation Scorpius is one of the twelve Zodiac constellations, lying along the ecliptic. The Moon and planets all traverse this constellation in their paths across the sky. Seen as a scorpion in ancient times, the constellation Libra represented its claws in Babylonian times. Antares is the red beating heart.

Scorpius is beautifully positioned due south currently for northerners, in the predawn skies.


Tuesday March 10

Get your telescope or binoculars out this morning for a view of two globular clusters just off Antares in Scorpius. M4 resolves into hundreds of stars in a telescope. It is about 7900 light years distant and very bright at magnitude 5.9, and visually about the size of our full Moon. Nearby, almost in the glow of Antares is NGC 6144, a 4.9′ magnitude 9 glow that will not resolve into individual stars. This smaller, dimmer globular is located 33,000 light years away. Nice contrast between this two similar objects!


Wednesday March 11

NGC 2903 is sometimes referred to as the “forgotten Messier.” It is certainly bright and big enough to warrant inclusion in the famous catalog. And it is easy to locate off the “tip of the nose” in Leo. Easiest is to use Regulus to move up the Sickle, then extend beyond it to the nearest bright star, and drop down slightly. At magnitude 9.7 and a generous size of 12.6’x6.0′, this galaxy discovered by Sir William Herschel is a great target.


Thursday March 12

An hour before sunrise the Moon and Saturn are paired three degrees apart high up in Scorpius. The soft creamy yellow glow of Saturn will be very apparent contrasted against the whiteness of 21 day old waxing gibbous moon, 62% illuminated.


Friday March 13

The last quarter Moon occurs today, and will be located in Ophiuchus an hour before sunrise. The position of the moon allows us to see the “bottom line” of Ophiuchus easily, as two pair of stars, one pair wide, and the other close. Another pair extends west into Serpens Caput.

A last quarter Moon on a weekend is especially nice, as it rises late, affording us plenty of dark sky time to observe dim targets such as galaxies and nebulae. Lucky us, on this Friday the 13th!


Saturday March 14

Revisit Canis Major this evening, for a look at two interesting open clusters. M41 is a large and classic open cluster you’ll see in binoculars. This cluster is thought to have been known by Aristotle, around 325 B.C. It is a bit larger than a full Moon, and bright enough to be seen naked-eye at magnitude 4.5. NGC 2362 will require a telescope. It is stunning, with the extremely large and luminous star Tau Canis Majoris at its center. A fun trick of the eye is to tap your telescope when viewing, and watch Tau jump around while the other stars seem almost stationary!

Happy viewing!