Astronomy Picture of the Day: 11/30/13 - The Dolphin Nebula

This is SH2-188 - otherwise known as the Dolphin Nebula - a planetary nebula that"s located approximately 850 light-years from Earth in the constellation of Cassiopeia A.

In the past, SH2-188 was thought to be the remnant of a supernova explosion that appeared in 1965 (it took the light 850 years to reach us), but the nebula was later confirmed to be an asymmetrical planetary nebula with a crescent-like shape. Most planetary nebulae simply have symmetrical shells that expand outwards, forming something similar to a shell around the dying star.

It"s thought that this nebula gets its interesting shape as a result of its travels. At the moment, it is traveling much faster than usual whilst interacting with the interstellar medium. The sun-like star responsible for expelling all of the gases into space thought to be moving at about 125 km/sec, which is almost 280,000 mph! As you can see, there is a bright southeastern arc in this image, which is the bow shock. The northwestern structure is a trailing tail of gases.

Sources & Further Reading: http://www.fromquarkstoquasars.com/astronomy-picture-of-the-day-112913-the-dolphin-nebula/

Image Credit: Canada-France-Hawaii Telescope/Coelum

7 Spooky Nebulae (Just in Time For Halloween)

Now that fall is officially upon us, in the spirit of Halloween, we thought we"d take the opportunity to dredge up some of our favorite scary nebulae. Most nebulae are truly lovely, containing an array of colors that are laid out so beautifully, they more closely resemble a painting than a scene of utter death and destruction. Granted, the nebula generally signify rebirth (long down the road, that is), and they look like places of great creation; yet occasionally, we run across some that are truly haunting. Like the ones outlined below:
-------------------------

7. The Witch Head Nebula:

Obviously, this is the witch head nebula. Of course, it is named as such because of its resemblance with the face of an evil witch, something you might expect to see in a fairytale (or in congress).

Instead, IC 2118 (as it is officially named) is a large nebula found about 900 light-years away, near the supergiant Rigel in the Orion constellation. The Witch Head has a deep blue color (as opposed to the typical green that we associate with witches). This color is not only because of the blue light emitted by Rigel, but also because the dust that makes up the nebula reflects blue light most efficiently (this same principle is the reason Earths sky appears blue).

See more terrifying nebulae at: http://www.fromquarkstoquasars.com/7-spooky-nebulae-just-in-time-for-halloween/

Astronomy Picture of the Day: 10/25/13 - Sharpless 2-68

What do you see in this newly released image from the Kitt Peak National Observatory? Personally, I see a demented Pac-Man-like creature.

This elderly planetary nebula is an estimated 45,000 years old. Planetary nebulae (one of the final phases of stellar evolution for a sun-like star) form after medium sized stars burn the remainder of hydrogen fuel forged at their core for nuclear fusion. After which, they burn helium, causing them to balloon in size. Eventually, the remainder of the mass will condense into a white-dwarf -- a dense remnant that is similar in size to Earth, with the outer envelope of gases shedding off into space, forming a nebula, which will eventually dissipate entirely.

Sharpless 2-68 (or Sh2-68), as it"s called, contains quite a bit of ionized oxygen atoms (pictured in blue), while the diffuse orange emission is the result of the nebula"s journey through the disk of our galaxy. At the center (in the blue haze) is the star responsible for the nebula"s existence.

References, sources, and further reading can be found here: http://www.fromquarkstoquasars.com/astronomy-picture-of-the-day-102513-sharpless-2-68/