Deep Sky Observing

Articles about how to understand, find, and see celestial objects including stars, galaxies, nebulae, and star clusters with binoculars, telescopes, and the naked eye.

The Beehive Cluster

April 7, 2017 by Brian Ventrudo Filed Under: Deep Sky

The Beehive Star Cluster (Messier 44) in the constellation Cancer. Credit: Marc Van Norden - Flickr) — The Beehive Star Cluster (Messier 44) in the constellation Cancer. Credit: Marc Van Norden – Flickr/CC License)

The constellation Cancer is the faintest of the twelve constellations of the zodiac, and many casual stargazers pass it by when looking from bright Gemini to the striking group Leo to the east. In city skies, the constellation is hard to see at all. But there are some excellent sights in Cancer within reach of a telescope, including the superb star cluster M44, the Beehive Cluster, which is one of the finest objects for a wide-field telescope or a pair of binoculars [Read more…] about The Beehive Cluster

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Castor and Pollux

March 17, 2017 by Brian Ventrudo Filed Under: Deep Sky

Gemini is still well overhead, north and east of the constellation Orion, in the evening hours in March. Its brightest stars are Castor and Pollux. Created with SkyX Serious Astronomer edition by Software Bisque.

Along with Taurus, Gemini is one of the two most northerly constellations of the zodiac. It lies just east of Auriga and the bright star Capella, and it’s marked by the two bright stars Castor and Pollux which lie less than 5º apart (a little less than the width of your three middle fingers held at arm’s length). To find the constellation draw an imaginary line diagonally from Rigel past Betelgeuse in the constellation Orion about a distance equal to the separation of these two bright stars. This will land you smack in the middle of Gemini. In March and April, the constellation lies still well above the western horizon in the early evening hours [Read more…] about Castor and Pollux

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The Bluest Star

March 10, 2017 by Brian Ventrudo Filed Under: Deep Sky

An artist's impression of the outer layers of the star Naos (zeta Puppis). Credit: Wikipedia. — An artist’s impression of the outer layers of the star Naos (zeta Puppis). Credit: Wikipedia.

Scattered in a thick band south of Canis Major lie the stars and star clusters of the constellation Puppis. There are no stars here to visually rival the brilliant stars of the Big Dog or Orion further to the north and west. But visual appearances are deceiving because among the stars of Puppis is one of the most luminous and hottest stars in our part of the galaxy, the star Naos or zeta Puppis [Read more…] about The Bluest Star

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A Little Cluster in the Big Dog

February 16, 2017 by Brian Ventrudo Filed Under: Deep Sky

NGC 2362, the Tau Canis Majoris cluster. Credit: Adam Block/Mount Lemmon SkyCenter, University of Arizona.

The constellation Canis Majoris, the ‘Big Dog’, is home to many fine open clusters of blue-white stars along the stubby Orion Arm of the Milky Way. There are some real gems here, including the modest but delightful open star cluster NGC 2362, a group that hosts some of the youngest-known stars. Centered on the bright star τ (tau) Canis Majoris, this cluster, in a telescope, looks like a large diamond set among many smaller blue-white gems [Read more…] about A Little Cluster in the Big Dog

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NGC 2477 – The Electric Guitar Cluster

February 10, 2017 by Brian Ventrudo Filed Under: Deep Sky

NGC 2477 (also known as Caldwell 71) is an open cluster in the constellation Puppis. It contains about 300 stars, and was discovered by Abbe Lacaille in 1751. The cluster's age has been estimated at about 700 million years. NGC 2477 is a stunning cluster, almost as extensive in the sky as the full moon. It has been called "one of the top open clusters in the sky", like a highly-resolved globular cluster without the dense center characteristic of globular clusters. Credit: J. Perez/ESO. — NGC 2477 (left) and NGC 2451 (right) are one of the most beautiful pairs of star clusters in the sky Credit: J. Perez/ESO.

We turn our gaze to the southern reaches of the constellation Puppis, south and east of the bright star Sirius and Canis Major, to examine two stunning star groups in a rich field of the Milky Way.

The first stop is the star cluster NGC 2477. Discovered by Nicolas de Lacaille (the ‘father of southern astronomy’) in 1752, this is a glorious star cluster, bright enough to be visible without optics from southern latitudes. It’s a fantastic binocular object, but it’s best viewed at low-power with a small telescope where it fits in the same field of view as an adjacent star cluster, NGC 2451. At a distance of 3,700 light years, NGC 2477 is one of the richest and densest of open star clusters and looks a little like the loose globular cluster M71 in the constellation Sagitta. The cluster has an impressive 1,900 members and spans about 37 light years. It’s also an ancient cluster, about 1 billion years old, and likely has lost many members since its birth to gravitational perturbations from other stars and star clusters [Read more…] about NGC 2477 – The Electric Guitar Cluster

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