Ruimtefotografie

Could life exist beneath Enceladus? A recent flyby of Saturn's icy moon has bolstered this fascinating idea. Two years ago, images from the robotic Cassini spacecraft orbiting Saturn led astronomers to the undeniable conclusion that Saturn's moon Enceladus was spewing fountains of gas and ice crystals through cracks in its surface dubbed tiger stripes. Last month, Cassini dove through some of these plumes and determined that they contained water vapor laced with small amounts of methane as well as simple and complex organic molecules. Surprisingly, the plumes of Enceladus appear similar in make-up to many comets. What's more, the temperature and density of the plumes indicate they might have originated from a warmer source -- possibly a liquid source -- beneath the surface. A liquid water sea containing organic molecules is a good place to look for life. Pictured above is a vertically exaggerated close-up of some long, venting tiger stripes. The computer composite was generated from images and shadows taken during the recent Cassini flyby. Nine more flybys of Enceladus by Cassini are planned.

De Gum nevel

Named for Australian astronomer Colin Stanley Gum (1924-1960), The Gum Nebula is so large and close it is actually hard to see. In fact, we are only about 450 light-years from the front edge and 1,500 light-years from the back edge of this cosmic cloud of glowing hydrogen gas. Covered in this 41 degree-wide mosaic of H-alpha images, the faint emission region is otherwise easy to lose against the background of Milky Way stars. The complex nebula is thought to be a supernova remnant over a million years old, sprawling across the southern constellations Vela and Puppis. Sliding your cursor over this spectacular wide field view will reveal the location of objects embedded in The Gum Nebula, including the Vela supernova remnant.

Zandduinen op Mars

What are these strange shapes on Mars? Defrosting sand dunes. As spring now dawns on the Northern Hemisphere of Mars, dunes of sand near the pole, as pictured above, are beginning to thaw. The carbon dioxide and water ice actually sublime in the thin atmosphere directly to gas. Thinner regions of ice typically defrost first revealing sand whose darkness soaks in sunlight and accelerates the thaw. The process might even involve sandy jets exploding through the thinning ice. By summer, spots will expand to encompass the entire dunes. The Martian North Pole is ringed by many similar fields of barchan sand dunes, whose strange, smooth arcs are shaped by persistent Martian winds.

Krabnevel

This is the mess that is left when a star explodes. The Crab Nebula, the result of a supernova seen in 1054 AD, is filled with mysterious filaments. The filaments are not only tremendously complex, but appear to have less mass than expelled in the original supernova and a higher speed than expected from a free explosion. The above image, taken by the Hubble Space Telescope, is presented in three colors chosen for scientific interest. The Crab Nebula spans about 10 light-years. In the nebula's very center lies a pulsar: a neutron star as massive as the Sun but with only the size of a small town. The Crab Pulsar rotates about 30 times each second.

M31

The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy some two and a half million light-years away. But without a telescope, even this immense spiral galaxy - spanning over 200,000 light years - appears as a faint, nebulous cloud in the constellation Andromeda. In contrast, a bright yellow nucleus, dark winding dust lanes, gorgeous blue spiral arms and star clusters are recorded in this stunning telescopic digital mosaic. While even casual skygazers are now inspired by the knowledge that there are many distant galaxies like M31, astronomers seriously debated this fundamental concept only 80 years ago. Were these "spiral nebulae" simply outlying components of our own Milky Way Galaxy or were they instead "island universes" -- distant systems of stars comparable to the Milky Way itself? This question was central to the famous Shapley-Curtis debate of 1920, which was later resolved by observations of M31 in favor of Andromeda, island universe.

M51

Die is de M51. Eigenlijk zijn het twee sterrenstelsels die met elkaar ‘verbonden’ zijn. Een foto als deze kan niet vanaf de aarde gemaakt worden, hij werd dan ook vanuit de Hubble gemaakt. (Dit is niet dezelfde als de M74.)

Dansen in de ruimte

Het lijkt verdomd een mannetje van Dirkje Kuik!

Halve maan

Deze prachtige foto is een paar jaar geleden gemaakt door de ruimtesonde Galileo. Het is de maan Europa van Jupiter, hij is ongeveer even groot als onze maan. Hij heeft geen inslagen van meteorieten gehad en heeft dus een zeer vlak oppervlak, dat bestaat uit ijsvelden die dichtvriezen en weer smelten. Daaronder vermoedt men een 100 km diepe oceaan (Europa heeft meer water dan de aarde), waarin zich leven zou kunnen bevinden.
En zo komen er elke dag de mooiste ruimtefoto’s vrij. Zou er een Nederlandse blogger zijn - eentje met enig verstand van zaken natuurlijk - die zich in dit soort fotografie specialiseert?

Een perfecte spiraal

Dit is M74, een sterrenstelsel dat zich zo’n 32 miljoen lichtjaren van ons af bevindt. Het telt ongeveer 100 miljard zonnen. We weten niet of er ook planeten zoals de aarde met zijn maan ronddraaien, maar de statistische kans dat er minstens één zo’n planeet ronddraait, is groot. En dit is nog maar één ander sterrenstelsel.

Volle aarde