Two Fine Spiral Galaxies Near the Dipper’s Handle

Messier 51, the Whirlpool Galaxy, and its companion NGC 5195. Credit: Terry Hancock at Downunderobservatory.com

Messier 51, the Whirlpool Galaxy, and its companion NGC 5195. Credit: Terry Hancock at Downunderobservatory.com

The stars of the Big Dipper are a wonderful guide to a handful of splendid galaxies and other deep-sky sights. Above and below the handle of the Dipper, most vividly, lie two stately face-on spiral galaxies that are visible, at least to some degree, in a small telescope. In dark skies, these two nearby galaxies display clear hints of a striking and naturally ubiquitous pinwheel shape that also reveals itself in the clouds of a hurricane or the seed arrangement in a sunflower…

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Star Tour – Cor Caroli and “La Superba”

An artist's rendering of the carbon star La Superba in the constellation Canes Venatici. Credit: Wikipedia Commons.

An artist’s rendering of the carbon star La Superba in the constellation Canes Venatici. Credit: Wikipedia Commons.

Turn your gaze to the sky under the handle of the Big Dipper and you’ll see only two reasonably bright stars. These are the 3rd-magnitude stars Cor Caroli and 4th-magnitude Chara. Cor Caroli (the “Heart of Charles”) was named by Edmund Halley after the martyred English King Charles I. It is a pretty double star, easily split in a small telescope even at 30-40x. The blue-white primary shines at magnitude 2.9; the fainter yellow companion is magnitude 5.6 some 19 arc-seconds away from the primary. The pair is about 110 light years away…

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The Beehive Cluster

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…

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The Sky This Month – April 2017

The planet Jupiter (credit: NASA)

The planet Jupiter (credit: NASA)

1 April. Mercury reaches its greatest eastern elongation at 19° from the Sun. In the northern hemisphere, the speedy little planet is at its highest altitude of the year. Look for Mercury low over the western horizon about half an hour after sunset. The planet shines at a respectably bright magnitude -0.2 and, in a telescope, reveals a half-lit disk. Slightly fainter and much redder Mars lies about a fist’s-width above Mercury. Over the next week, you will see Mercury plunge back towards the horizon as it quickly makes its way around the Sun…

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Castor and Pollux

Gemini is still well overhead, north and east of the constellation Orion, in the evening hours in March.

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…

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The Bluest Star

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…

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The Sky This Month – March 2017

Waiting-for-Darkness-Winter-Star-Party-2017

Waiting for astronomical twilight at the Winter Star Party near Big Pine Key, Florida, on February 24, 2017.

1 March 2017. The Moon returns at the beginning of March in the form of a slender waxing crescent in the western sky after sunset. It’s joined by the fading but still respectably bright planet Mars and the unmistakable silver-white radiance of the planet Venus. Uranus lies 2º west of Mars and reveals itself easily in a pair of binoculars. These three planets are a study in contrasting brightness. Venus shines at magnitude -4.6, Mars at magnitude +1.3, and Uranus at magnitude +5.7. The Moon today has a total magnitude of -9.0. Each full step in magnitude is a factor of 2.512 in brightness…

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A Little Cluster in the Big Dog

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

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…

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NGC 2477 – The Electric Guitar Cluster

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…

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The Sky This Month – February 2017

The full Moon is partially in the Earth's shadow during a penumbral lunar eclipse. Credit: Radoslaw Ziomber/Wikipedia Commons.

The full Moon is partially in the Earth’s shadow during a penumbral lunar eclipse. Credit: Radoslaw Ziomber/Wikipedia Commons.

2 February 2017. Look for the bright white star Spica in the constellation Virgo and the much brighter planet Jupiter in the southeastern sky well before sunrise. The pair lie within about two finger widths of each other for most of the month.

2-3 Feb. The dwarf planet Ceres lies about 1º south of the waxing crescent Moon. Some observers across southern Europe, North Africa, Central America, and northern South America will see the little world pass behind the Moon at roughly 02:00 UT on Feb. 3. Ceres shines at about 9th magnitude, easy to see in binoculars or a telescope, although the glare of the Moon makes it a little harder to spot. Ceres is the largest of the dwarf planets in the asteroid belt. It’s a nearly round world with a diameter of 950km. That makes it the 33rd largest object in the solar system…

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