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Find Canes Venatici high in the south after dark tonight to go hunting for NGC 4631 — an edge-on spiral also known as the Whale Galaxy.
The Whale Galaxy (NGC 4631) in Canes Venatici is a great deep-sky target for large scopes, particularly with the New Moon on the 16th. Above the larger Whale Galaxy is dwarf galaxy NGC 4627. Credit: Mark Phillips (Flickr, CC BY-NC-SA 2.0)
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May 15: A double shadow transit at Jupiter
New Moon occurs at 4:01 P.M. EDT, leaving the evening sky perfect for deep-sky observing.
By 10 P.M. local time, the sky should be dark. High in the south is the constellation Canes Venatici, where our target for tonight is located. We’re hunting down NGC 4631, also known as the Whale Galaxy. You’ll find it just 6.5° south-southwest of Cor Caroli (Alpha [α] Canum Venaticorum), which shines at magnitude 2.9.
The Whale glows softly at magnitude 9.2, stretching some five times longer than it is wide (15’ by 3’). Try an 8-inch or larger scope with a magnification of 200x to see detail. This galaxy is an edge-on spiral, meaning we’re looking directly into the plane of the disk. You may notice a mottled appearance, caused by dust lanes blocking out light along the galaxy’s brighter disk. It is thicker toward the east than the west, giving the object the appearance of a whale with a larger, rounder head and body that taper into a thinner tail.
You may also notice a tiny dwarf galaxy, NGC 4627, nearby, glowing at 12th magnitude to the Whale’s northwest. The pair is indeed close in real space as well — the two galaxies have interacted in the past, triggering a burst of bright star formation in the larger Whale.
Sunrise: 5:44 A.M.
Sunset: 8:09 P.M.
Moonrise: 5:07 A.M.
Moonset: 8:36 P.M.
Moon Phase: New
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.