Cosmic Pursuits

Basic astronomy and night sky information

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.

Sightseeing along the Perseus Arm of the Milky Way

by Brian Ventrudo Filed Under: Deep Sky

A section of the Perseus Arm of the Milky Way looking overhead from the northern hemisphere in winter.

In the early months of each year, stargazers south of the equator enjoy a dazzling view of a rich part of the Milky Way, one that’s festooned with open star clusters, emission nebulae, and bright blue-white stars. Here, in the constellations Centaurus and Crux, we gaze into one of the two major spiral arms of the Milky Way, the Scutum Centaurus Arm, that originates from the long bar of ancient stars at the core of our galaxy.

An observer looking overhead in the northern hemisphere sees a completely different perspective. Here the view lies in a direction away from the center of the galaxy into the outer reaches of the Perseus Arm, the second major spiral arm that emanates from the galactic core [Read more…] about Sightseeing along the Perseus Arm of the Milky Way

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The Taurus Molecular Cloud

by Brian Ventrudo Filed Under: Deep Sky

The Taurus Molecular Cloud, to the lower left of the Pleiades and lower right of the California Nebula in this wide-field image. The Hyades star cluster in Taurus is at middle right; the star Capella in the constellation Auriga is the bright star at left. Image credit: Brian Ventrudo

Not far from the Pleiades and Hyades star clusters along the northern Milky Way lies the coal-black fingers of the Taurus Molecular Cloud, the nearest star-forming region to Earth. Unlike the more famous Orion star factory, with the dazzling Orion Nebula and associated bright blue-white stars, the TMC is not well known to most stargazers. That’s because it doesn’t offer much to see, with no bright nebulae and just a dark and sooty network of tendrils that span more than 30o of sky. But the TMC is the nearest star-forming region to Earth, making it of considerable interest to astronomers. It’s also a rewarding target for astrophotographers who can capture its structure against the starry background in the constellations Taurus and Auriga [Read more…] about The Taurus Molecular Cloud

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Nebula Hopping in the Constellation Cygnus

by Brian Ventrudo Filed Under: Deep Sky

The North America Nebula (on its side) and above it the Pelican Nebula in the constellation Cygnus.

Like many constellations along the arc of the Milky Way, the constellation Cygnus harbors an embarrassment of celestial riches. There’s everything here: emission nebula, supernova remnants, open star clusters, star clouds, and dark nebulae that reach like intertwined fingers over the bright and unresolved star clouds in this part of the sky. In dark sky, with a pair of binoculars or wide-field telescope, a contemplative stargazer can spend many happy hours hopping from object to object, wondering why more people turn their eyes skyward more often.

Which is what I was doing on a cool northern autumn night as I toured the celestial Swan, looking for a handful of pretty emission nebulae that radiate a deep red light and stand out along the rich star field in this part of the sky. These nebulae make ideal targets for urban stargazers like me because their contrast is readily enhanced with a good light pollution filter which passes their emission while reducing the effect of urban light pollution. The nebula doesn’t appear brighter, but it does have better contrast against fish-grey urban and suburban skies [Read more…] about Nebula Hopping in the Constellation Cygnus

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The Veil Nebula

by Brian Ventrudo Filed Under: Deep Sky

The Veil Nebula in the constellation Cygnus. The right section (NGC 6960) overlaps with the star 52 Cygni. The brighter arc at left is NGC 6992. In between lies Pickering’s Triangle. Click image to enlarge in a new window. Image credit: Brian Ventrudo/Cosmic Pursuits.

“It’s better to burn out than to fade away”, as Neil Young once said, and when it comes to burning out nothing beats a big star that blows up as a supernova. These catastrophic events occur as big stars run out of fuel in their core and become unable to hold themselves up against the relentless pull of their own gravity. Their outer layers collapse, crush the star’s dense core into a neutron star or black hole, then snap back in a violent explosion that eject as much energy in a few minutes as our sun does in its entire lifetime.

Since only the largest stars expire like this, and since the explosion itself plays out quickly over a few days or weeks, a supernova is a relatively rare event: the last known supernova in the Milky Way happened more than 400 years ago. But such explosions often leave a long-lasting imprint in the form of a visible nebula caused by the rapidly expanding shock wave of the exploding star colliding with and setting aglow the rarefied gas of the interstellar medium. Dozens of these so-called supernova remnants fleck the night sky. Most require a big telescope and sensitive camera to detect, but one of the brightest and easiest to see lies off the eastern ‘wing’ of the constellation Cygnus, the Swan. This is the famous Veil Nebula, a sprawling complex of glowing gas and one of the most intricate and intrinsically beautiful objects in our galaxy [Read more…] about The Veil Nebula

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The ‘North America’ Nebula

by Brian Ventrudo Filed Under: Deep Sky

The North America Nebula and associated dark nebulae and star clouds in the constellation Cygnus. The bright star Deneb, at right, formed a halo as a result of passing haze during the imaging session. Image credit: Brian Ventrudo.

Just off the tip of the Northern Cross (or the tail of Cygnus, the Swan) lies the photogenic NGC 7000, an immense star-forming complex embedded in rarefied hydrogen gas set aglow by massive blue-white stars. This emission nebula has an evocative shape that resembles the continent of North America which lends its informal name. Unlike more compact and concentrated nebula like the Swan or Orion Nebulae, the North America Nebula is a challenging object to spot visually. But it’s always a treat to see its faint ethereal glow emerging from the starry background of the northern Milky Way. [Read more…] about The ‘North America’ Nebula

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