What's Up in the Sky - May 2015
At any moment of the day, countless awe-inspiring celestial events are unfolding in the sky. With a universe of options, it can be hard to pin down what to observe, what to look into or what to remember. This column takes a peek at what’s happening in the sky and in the world of astronomy in general to provide a quick list of highlights that can jumpstart your own explorations.
What to observe:
May 23 – Saturn at Opposition
Saturn and its dazzling rings will be in a prime viewing position as the planet reaches opposition at 0200 UT on May 23rd (9 p.m. CDT on May 22nd in the U.S.). During this event, Saturn will be positioned directly opposite of the Sun when viewed from Earth. It will rise as the Sun sets and stay up all night, which provides for ample viewing time. In addition to delving into Saturn’s fascinating ring system, small telescope users might want to look for Titan, the largest of Saturn’s moons, and the dark groove in the rings that is identified as the Cassini Division. Although Saturn just moved into the Libra Constellation, the quickest way to locate it is to look for it in the east above the red-hued beauty known as Antares in the Scorpius Constellation. To the naked eye, it will appear as a steady, gold point of light. Following opposition, Saturn will remain a brilliant showpiece of the night sky for several months.
Offering up a feast of intriguing galaxies, the Virgo constellation is an ideal May target for stargazers in either hemisphere. As the second largest constellation, Virgo covers 1,294 square degrees of celestial real estate and is visible from 80° North to 80° South.
Before dipping into all of Virgo’s galactic offerings, a new observer can get their bearings by locating the constellation’s standout star - Spica. Also known as alpha Virginis, this multi-star system dominated by a blue giant has an apparent visual magnitude of 1.04. To easily locate Spica, find the Big Dipper asterism and follow the arc of its handle as it points to Arcturus, an orange giant star in the Bootes constellation. Once your eye finds Arcturus, continue to follow the same gentle curve to the blue-white beauty Spica. Some of Virgo’s other stellar treats include Porrima, a binary star system that can only be resolved with large aperture telescopes; Auva, a red giant with variations in brightness; Vindemiatrix, a yellow giant with an apparent visual magnitude of 2.826; Heze, a white dwarf; and Zavijava, an often-occulted pale star that stays cozy with the ecliptic plane and gained a bit of notoriety when it was used by Einstein in 1922 to determine the speed of light in space.
Virgo really starts to shine when it comes to deep sky observing targets. One of Virgo’s most dynamic deep sky treasures is the Sombrero Galaxy (Messier 104), which is located about 11.5° west of Spica. Featuring between 1,200 to 2,000 globular clusters, this unbarred spiral galaxy has a bright bulging center ringed by a pronounced dark dust lane. The huge constellation also is home to the massive Virgo Cluster, which teems with a versatile mix of well over a thousand galaxies. Among its offerings are Messier 49, an elliptical galaxy with a 9.4 visual magnitude that makes it the cluster’s brightest member; Messier 87, a giant elliptical galaxy with a 9.59 visual magnitude that lies near Virgo’s border with the Coma Berenices constellation; Messier 58, a barred spiral galaxy; and the lenticular galaxies Messier 84 and Messier 86. The cluster also includes the Siamese Twins (NGC 4567 AND NGC 4568), which are colliding spiral galaxies; the Eyes Galaxies, which includes the barred lenticular NGC 4435 and the hard-to-categorize NGC 4438; the bright Messier 88 and Messier 90 spiral galaxies and the challenging Messier 91 barred spiral galaxy.