NGC 253: Dusty Island Universe

Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest. Some call it the Silver Dollar Galaxy for its appearance in small telescopes, or just the Sculptor Galaxy for its location within the boundaries of the southern constellation Sculptor. Discovered in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies. In addition to its spiral dust lanes, tendrils of dust seem to be rising from a galactic disk laced with young star clusters and star forming regions in this sharp color image. The high dust content accompanies frantic star formation, earning NGC 253 the designation of a starburst galaxy. NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to massive black holes near the galaxy's center. Take a trip through extragalactic space in this short video flyby of NGC 253.

Camera Orion

Do you recognize this constellation? Although it is one of the most recognizable star groupings on the sky, Orion's icons don't look quite as colorful to the eye as they do to a camera. In this 20-image digitally-composed mosaic, cool red giant Betelgeuse takes on a strong orange tint as the brightest star at the upper left. Orion's hot blue stars are numerous, with supergiant Rigel balancing Betelgeuse at the lower right, and Bellatrix at the upper right Lined up in Orion's belt are three stars all about 1,500 light-years away, born from the constellation's well-studied interstellar clouds. Below Orion's belt a reddish and fuzzy patch that might also look familiar -- the stellar nursery known as Orion's Nebula. Finally, just barely visible to the unaided eye but quite striking here by camera is Barnard's Loop -- a huge gaseous emission nebula surrounding Orion's Belt and Nebula discovered over 100 years ago by the pioneering Orion photographer E. E. Barnard.

The Nebra Sky Disk

It is considered the oldest known illustration of the night sky. But what, exactly, does it depict, and why was it made? The Nebra sky disk was found with a metal detector in 1999 by treasure hunters near Nebra, Germany, in the midst of several bronze-age weapons. The ancient artifact spans about 30 centimeters and has been associated with the Unetice culture that inhabited part of Europe around 1600 BC. Reconstructed, the dots are thought to represent stars, with the cluster representing the Pleiades, and the large circle and the crescent representing the Sun and Moon. The purpose of the disk remains unknown -- hypotheses including an astronomical clock, a work of art, and a religious symbol. Valued at about $11 million, some believe that the Nebra sky disk is only one of a pair, with the other disk still out there waiting to be discovered.

Rotating Moon from LRO

No one, presently, sees the Moon rotate like this. That's because the Earth's moon is tidally locked to the Earth, showing us only one side. Given modern digital technology, however, combined with many detailed images returned by the Lunar Reconnaissance Orbiter (LRO), a high resolution virtual Moon rotation movie has been composed. The above time-lapse video starts with the standard Earth view of the Moon. Quickly, though, Mare Orientale, a large crater with a dark center that is difficult to see from the Earth, rotates into view just below the equator. From an entire lunar month condensed into 24 seconds, the video clearly shows that the Earth side of the Moon contains an abundance of dark lunar maria, while the lunar far side is dominated by bright lunar highlands. Currently, over 20 new missions to the Moon are under active development from four different countries, most of which have expected launch dates either this year or next.

The Crab from Space

The Crab Nebula is cataloged as M1, the first object on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, expanding debris from the death explosion of a massive star. This intriguing false-color image combines data from space-based observatories, Chandra, Hubble, and Spitzer, to explore the debris cloud in X-rays (blue-white), optical (purple), and infrared (pink) light. One of the most exotic objects known to modern astronomers, the Crab Pulsar, a neutron star spinning 30 times a second, is the bright spot near picture center. Like a cosmic dynamo, this collapsed remnant of the stellar core powers the Crab's emission across the electromagnetic spectrum. Spanning about 12 light-years, the Crab Nebula is 6,500 light-years away in the constellation Taurus.

NGC 253: Dusty Island Universe

Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest. Some call it the Silver Dollar Galaxy for its ...