These free, printable Sky Maps (star charts) by astronomer Jeff DeTray will help find your way around the night sky!
Each month, Jeff’s Sky Maps highlight a wonderful event in the evening sky—including beautiful stars, constellations, planets, conjunctions with the Moon, meteor showers, and other amazing celestial objects.
Sky Map April 2015
By Jeff DeTray, Almanac astronomer writer
Follow Jeff DeTray’s sky adventures at AstronomyBoy.com
This Month: Jupiter and the Beehive
Just click, print, and bring outside!
Jupiter blazes bright in the southern sky throughout the month of April.
Our largest planet spends the whole month in the constellation Cancer, the Crab. Cancer is a rather unimpressive constellation, but in addition to hosting Jupiter this month, it contains a well-known star cluster that has
Today, the cluster is most commonly called the Beehive Cluster. It is so-named because many observers think that the appearance of the cluster in a small telescope resembles a swarm of bees. It is an example of an “open cluster,” a group of stars that evolved together from a large cloud of molecules and are all about the same age. The stars’ gravity holds the
cluster together, and the stars of the cluster move through space as a group.
In 1609, Galileo observed this cluster—he knew it as Praesepe (Latin for “manger”)—and thought that it contained about 40 stars. We now know that there are approximately 1,000 stars in the Beehive Cluster.
Furthermore, Praesepe was well known to the ancient Greeks and Romans long before Galileo invented the telescope. This means that you, too, do not necessarily need a telescope or even binoculars to catch a glimpse of the cluster. What you do need is a very dark, rural location far from city lights. In these conditions, you may be able to see the Beehive as a small, hazy patch at the location shown on our Sky Map. Its appearance gives the cluster another of its more ancient names: the Little Cloud. None of the individual stars in the cluster is visible to our unaided eyes, but their combined light can be seen as the Little Cloud.
In the 18th century, French astronomer Charles Messier was hunting comets. He regularly spotted objects that he initially believed to be comets, only to later determine that they were something else, such as star clusters or galaxies. To avoid wasting valuable observing time on these noncomets, Messier made a list of them and their locations. The star cluster that we call the Beehive was the 44th noncomet that Messier noted, hence another of its names: Messier 44, or simply M44.
The Messier List of noncomets eventually grew to include 110 celestial objects of many types. Messier considered them a nuisance to be avoided, but in modern times amateur astronomers have embraced the Messier List because it contains a nice cross-section of celestial objects—but no comets, of course!
To see another open cluster, turn your gaze to the left past Leo, the Lion, to another dim constellation, Coma Berenices, or Queen Berenice’s Hair. Coma Berenices is home to the Coma Berenices Star Cluster, also known as Melotte 111, being the 111th object in the Melotte Catalogue of Star Clusters compiled by French astronomer P. J. Melotte. It contains far
fewer stars than the Beehive but is much closer to us. As a result of its close proximity, the Coma Berenices Star Cluster is a little brighter and easier to see than the Beehive.
“Close proximity” is a relative term. The Coma Berenices Star Cluster is closer than the Beehive but still fantastically far away: 288 light-years, or about 1,700,000,000,000,000 miles. That’s 1.7 quadrillion miles!
In comparison, the planet Jupiter is a mere 462 million miles distant. This puts the Coma Berenices Star Cluster 3.6 million times farther from us than Jupiter. The Beehive is 7.5 million times more distant than Jupiter.
Sky map produced using Chris Marriott’s Skymap Pro
See our Sky Watch page for more highlights of the monthly sky, courtesy of The Old Farmer’s Almanac.