[via APOD]
What’s that bright object in the sky? A common question with answers that vary by time and season, the quick answer just after sunset in middle of last month, from the northern hemisphere, was Mars.
The above picturesque panorama, taken during a ski trip from the Alps in Switzerland, shows not only Mars, but much more. Pine trees line the foreground, while numerous slopes leading up to the snow covered Allalinhorn mountain are visible in the distance.
Put a satellite in a circular orbit about 42,000 kilometres from the center of the Earth (36,000 kilometres or so above the surface) and it will orbit once in 24 hours. Because that matches Earth’s rotation period, it is known as a geosynchronous orbit. If that orbit is also in the plane of the equator, the satellite will hang in the sky over a fixed location in a geostationary orbit.
As predicted in the 1940s by futurist Arthur C. Clarke, geostationary orbits are in common use for communication and weather satellites, a scenario now well-known to astroimagers.
[via APOD]
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What surrounds the florid Rosette nebula?
To better picture this area of the sky, the famous flowery emission nebula on the far right has been captured recently in a deep and dramatic wide field image that features several other sky highlights.
Designated NGC 2237, the center of the Rosette nebula is populated by the bright blue stars of open cluster NGC 2244, whose winds and energetic light are evacuating the nebula’s center. Below the famous flower, a symbol of Valentine’s Day, is a column of dust and gas that appears like a rose’s stem but extends hundreds of light years.
[via APOD]
The snow capped Teide volcano is reflected in a pool of water in this nearly symmetric night sky view from the Canary Island Tenerife.
Bright north star Polaris stands above the peak in an exposure that also captures the brilliant trail of a polar orbiting Iridium satellite.
Of course, with the camera fixed to a tripod, the stars themselves produce concentric trails in long exposures, a reflection of the Earth’s rotation around its axis.
Large astronomical observatories also take advantage of the calm Canary Island sky.
[via io9]
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Here are some vampires we don’t mind sparkling. This globular cluster, Messier 30, contains two types of ancient stars that have managed to keep themselves brilliant and young. One type relies on interstellar collisions; the other drinks from its neighbors.
Messier 30 is an unusual cluster. It’s an ancient cluster, and yet it is filled with blue stars, stars that tend to age and die more quickly than other types of stars. Astronomers have termed these unusually old blue stars “blue stragglers,” and they believe that there are two reasons these stars still exist.
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What lights up the Flame Nebula?
Fifteen hundred light years away towards the constellation of Orion lies a nebula which, from its glow and dark dust lanes, appears, on the left, like a billowing fire. But fire, the rapid acquisition of oxygen, is not what makes this Flame glow. Rather the bright star Alnitak, the easternmost star in the Belt of Orion visible just above the nebula, shines energetic light into the Flame that knocks electrons away from the great clouds of hydrogen gas that reside there. Much of the glow results when the electrons and ionized hydrogen recombine.
