Heads Up! – Planets Pair with Clusters

April 11 Venus & M45

Look west and south this weekend to see the two brightest planets each pairing with a bright cluster of stars.

This weekend, Venus and Jupiter each pair with a prominent open star cluster.

In the west, look for brilliant Venus, an evening “star” this spring, shining near the Pleiades, or Seven Sisters star cluster. Some know it as Messier 45.

Both Venus and the Pleiades are in Taurus the bull, whose main stars lie to the left of the Venus-Pleiades pairing. Farther to the left still, look for the distinctive stars of Orion the hunter, whose trio of Belt stars give him away.

April 11 Venus & M45 CU

As this close up shows, binoculars will nicely frame Venus and the Pleiades at once.

Venus continues to climb higher this spring while the Pleiades and the other stars of the winter sky, including Orion and Taurus, sink lower and lower. The next few nights are the best for catching Venus as it passes the Pleiades.

April 11 Jupter & M44

High in the south as it gets dark shines the other bright planet in our sky – Jupiter.

It, too pairs with a star cluster. Jupiter now shines a binocular field to the east (left) of the Beehive Cluster, also known as Messier 44. Jupiter and M44 lie in Cancer the crab, a faint constellation nestled between Leo to the east and Gemini to the west.

Jupiter has been retrograding closer to the Beehive all winter and early spring. But this weekend Jupiter sits as close to the cluster as it is going to get. For the rest of spring and summer Jupiter will move east away from the Beehive.

Look west and south as it gets dark this weekend, for the pair of planet-cluster pairings!

Clear skies and happy stargazing.

– Alan, April 9, 2015 / © 2015 Alan Dyer / www.amazingsky.com


Springtime Cluster #1: The Beehive (M44)

At last! A clear night in what so far has been an awful spring. The long-awaited arrival of mild spring nights brings a sky sprinkled with a few naked-eye star clusters. This is the most famous, and appears as a fuzzy glow in the constellation of Cancer the Crab. Indeed, to the unaided eye, there’s not much else to see in Cancer. But this cluster is a dandy in binoculars. Called the Beehive, this is one of the few deep-sky objects known since antiquity. Apparently, the Greek poet Aratos mentioned it in 260 B.C., describing it as a “little mist.” A hundred years later Hipparchus included it in his star catalog, calling it a “cloudy star.”

It wasn’t until 1609 that Galileo, using his pioneering telescope, resolved the cloud into a mass of stars. Any binoculars will do the same today. This close-up view more closely matches the view through a modern telescope, showing its subtly coloured blue and yellow stars.

In 1769 Charles Messier included it as object #44 (the Pleiades was #45) in his first catalog of what we now call deep-sky wonders. To him, however, these fuzzy spots in the sky were just distractions to his goal of hunting the fuzzy things that really mattered – comets.

The stars of M44 really do belong together in a gravitationally-bound cluster of up to 1000 stars, traveling together through space since the time about 600 million years ago when they formed out of what must have been a massive gas cloud. That’s a pretty good age for a star cluster; most break apart and scatter around the Galaxy after just a few tens of millions of years. However, the Beehive sits about 600 light years away, above the main disk of the Milky Way and its spiral arms. Its location makes it partly immune to the disruptive tidal forces of the Galaxy. Because it lies above the galactic plane we see it far off the band of the Milky Way, shining in our spring sky sparsely populated with bright stars and lacking the rich assortment of clusters and nebulas scattered along the winter and summer Milky Way.

For this exposure I used a favourite scope, the TMB 92mm apo refractor, a compact and fast little telescope perfect for imaging big binocular-class objects like this. This is a stack of four 4-minute exposures at ISO 800 with the Canon 7D camera. A Photoshop routine added the diffraction spikes, purely for photogenic value.

– Alan Dyer, April 2011 / Image © 2011 Alan Dyer