Explanation: In order top to bottom
this celestial snapshot features Comet ISON, planet Mars, and Regulus, alpha
star of the constellation Leo, in the same frame. The scene spans about 2
degrees near the eastern horizon in early morning skies of October 15. Closest
of the three, the much heralded Comet ISON (C/2012 S1) is by far the faintest
at 14 light-minutes (1.7 AU) away. Mars is only slightly farther from our fair
planet. About 16.5 light minutes (2 AU) away its normal ruddy color is washed
out in the exposure. Regulus outshines both comet and planet from a distance of
75 light-years. Just above Regulus, the very faint smudge of light is actually
the Leo I dwarf galaxy, 800,000 light-years away and almost lost in the glare
of the bluish hued bright star. Comet ISON is expected to grow brighter,
though. How bright is still not clear, but not as bright as a Full Moon in
night skies. Estimated to be 1 to 4 kilometers in diameter, ISON's nucleus
might substantially survive its very close encounter with the Sun on November
28. If so, the comet will climb back above the eastern horizon in planet
Earth's northern hemisphere before dawn in early December.
هیچ نظری موجود نیست:
ارسال یک نظر