Here is the transcript for my podcast about how to see the
constellation Canes Venatici, the Whirlpool Galaxy, and the Whale Galaxy this week.
Check out the Astronomy.com's interactive star chart — StarDome — to see an accurate map of your sky. It'll help you locate some of this week's key targets. Astronomy magazine subscribers have access to a slew of cool functions with StarDome PLUS.
Each week, I highlight three different night-sky targets for you to see:
- One object you can find with your naked eyes or through binoculars
- One object to find with a small telescope
- One deep-sky object to find with an 8-inch or larger telescope for you avid astronomers
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Hunt for the Hunting Dogs
This week’s naked-eye object is the difficult-to-see constellation Canes Venatici the Hunting Dogs. This constellation only has three bordering star patterns: Ursa Major the Great Bear lies to the north and west; Coma Berenices the Hair of Berenice forms part of its southern border; and Boötes the Herdsman lies to the east and also completes the southern border.
In size, Canes Venatici ranks 38th out of the 88 constellations that cover the sky. It occupies 465 square degrees — that’s a respectable 1.13 percent of the sky.
The best time to see Canes Venatici is early April. That’s when the constellation lies opposite the Sun. It rises at sunset, sets at sunrise, and is visible in the sky all night. The worst time to look for Canes Venatici is in early October. That’s when its stars line up with the Sun.
Canes Venatici bustles with deep-sky objects. It contains five Messier objects within its borders: globular cluster M3, and spiral galaxies M51, M63, M94, and M106.
Finding Canes Venatici isn’t easy. It’s rated as the 5th faintest constellation in the sky. From a dark site, look just below the Big Dipper’s handle. The brightest star in this region — and that’s not saying much — is Cor Caroli (Alpha [α] Canum Venaticorum), which shines at magnitude 2.8. Canes Venatici’s only other reasonably bright star, Chara (Beta [β] Canum Venaticorum) lies 5° to the west-northwest and glows weakly at magnitude 4.3.
The sky’s best galaxy?
This week’s small telescope target is the spectacular Whirlpool Galaxy in my featured constellation, Canes Venatici. Also known as M51, the Whirlpool lies one-quarter of the way from magnitude 1.8 Alkaid (Eta [η] Ursae Majoris) to Cor Caroli.
Through a 4-inch telescope under a dark sky, you’ll see a circular glow with a bright core. A small bright area lies outside the fuzzy circle. That’s NGC 5195, a companion galaxy of M51. Although photographs appear to show a connecting arm between the two galaxies, this is an illusion.
Computer models indicate NGC 5195 passed close to the Whirlpool’s disk some 70 million years ago and then plunged through its plane. A 6-inch scope will begin to reveal M51’s spiral arms.
In 1845, William, Third Earl of Rosse, saw the spiral form of this object through his 72-inch reflector. M51 was the first galaxy to show such structure.
Thar’ she blows!
This week’s deep-sky target — also in Canes Venatici — is the Whale Galaxy, also known as NGC 4631. This magnificent edge-on galaxy sits 6.5° south-southwest of Cor Caroli.
The Whale Galaxy shines at magnitude 9.2. It measures 15' long and 3' wide at its thickest point. Now, here’s a celestial object an 8-inch telescope will do justice to. Under a dark sky, use a magnification around 200x.
The central region shines brightest, and the spiral arms have a mottled, salt-and-pepper appearance because of vast quantities of dust. The easternmost arm is much thicker than the one to the west. A tiny southern extension gives it the appearance of an arrowhead. The western arm tapers away from the core more gradually.
As you’ll probably notice, the Whale doesn’t swim through space alone. Look only 2.5' northwest of NGC 4631 for NGC 4627. This magnitude 12.0 dwarf elliptical galaxy has interacted with the Whale in the past, triggering intense star formation. In fact, the small galaxy is responsible for the irregular appearance of its large companion.
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Previous episode: Constellation Corvus the Crow, open cluster M67, and spiral galaxy NGC 2683