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Από την NASΑ: Αστρονομική φωτογραφία ημέρας

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Μία καινούρια φωτογραφία καθημερινά με μιά μικρή ερμηνεία του φαινομένου που παρουσιάζει.

Τα links των λέξεων της ερμηνείας που παραπέμπουν σε άλλες σελίδες δημιουργούν μιά πλήρη αστρονομική εγκυκλοπαίδεια...

Υπάρχει ημερολόγιο (kalendar) των φωτογραφιών στο site το οποίο λειτουργεί από το 1995 και πλούσιο ευρετήριο (Index)...

Με κλίκ στην κεντρική φωτογραφία την βλέπετε/κατεβάζετε και σε μεγαλύτερη ανάλυση... Δυστυχώς στα Αγγλικά βέβαια...


Μερικά παραδείγματα

A Darkened Sky


For a moment on August 1st, the daytime sky grew dark along the path of a total solar eclipse.

While watching the geocentric celestial event from Mongolia, photographer Miloslav Druckmuller recorded multiple images with two separate cameras as the Moon blocked the bright solar disk and darkened the sky.

This final composition consists of 55 frames ranging in exposure time from 1/125 to 8 seconds. It spans nearly 12 degrees, with the relative position of the Moon and Sun corresponding to mid-eclipse.

On the left is bright planet Mercury, but many stars are also visible, including the Praesepe star cluster (also known as M44 or the Beehive cluster) in Cancer, above and to the right of the silhouetted Moon.

Remarkably, the nearly perfect conditions and wide range in individual exposures allow the composite picture to register the lunar surface and follow the delicate solar corona out to a distance of nearly 20 times the radius of the Sun.

In fact, the composite presents a range in brightness beyond what the eye could see during the eclipse.

Credit & Copyright: Miloslav Druckmuller (Brno University of Technology), Peter Aniol, Vojtech Rusin

SN 1006


What created this unusual space ribbon?

Most assuredly, one of the most violent explosions ever witnessed by ancient humans. Back in the year 1006 AD, light reached Earth from a stellar explosion in the constellation of the Wolf (Lupus), creating a "guest star" in the sky that appeared brighter than Venus and lasted for over two years.

The supernova, now cataloged at SN 1006, occurred about 7,000 light years away and has left a large remnant that continues to expand and fade today.

Pictured above is a small part of that expanding supernova remnant dominated by a thin and outwardly moving shock front that heats and ionizes surrounding ambient gas.

SN 1006 now has a diameter of nearly 60 light years.

Within the past year, an even more powerful explosion occurred far across the universe that was visible to modern humans, without any optical aid, for a few seconds.

Credit: NASA, ESA, Hubble Heritage (STScI/AURA); Acknowledgement: W. Blair et al. (JHU)

Two Black Holes Dancing in 3C 75


What's happening at the center of active galaxy 3C 75?

The two bright sources at the center of this composite x-ray (blue)/ radio (pink) image are co-orbiting supermassive black holes powering the giant radio source 3C 75.

Surrounded by multimillion degree x-ray emitting gas, and blasting out jets of relativistic particles the supermassive black holes are separated by 25,000 light-years.

At the cores of two merging galaxies in the Abell 400 galaxy cluster they are some 300 million light-years away.

Astronomers conclude that these two supermassive black holes are bound together by gravity in a binary system in part because the jets' consistent swept back appearance is most likely due to their common motion as they speed through the hot cluster gas at 1200 kilometers per second.

Such spectacular cosmic mergers are thought to be common in crowded galaxy cluster environments in the distant universe. In their final stages the mergers are expected to be intense sources of gravitational waves.

Credit: X-Ray: NASA / CXC / D.Hudson, T.Reiprich et al. (AIfA);

Radio: NRAO / VLA/ NRL

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