Conjunction after Sunset - 2020-12-19

How close will Jupiter and Saturn be at their Great Conjunction? Consider this beautiful triple conjunction of Moon, Jupiter and Saturn captured through clouds in the wintry twilight. The telephoto view looks toward the western horizon and the Alborz Mountains in Iran after sunset on December 17. The celestial gathering makes it easy to see Jupiter and fainter Saturn are separated on that date by roughly the diameter of the waxing crescent Moon. On the day of their Great Conjunction, solstice day December 21, Jupiter and Saturn may seem to nearly merge though. In their closest conjunction in 400 years they will be separated on the sky by only about 1/5 the apparent diameter of the Moon. By then the two largest worlds in the Solar System and their moons will be sharing the same field of view in telescopes around planet Earth.  

A Blue Moon in Exaggerated Colors - 2021-08-31

The Moon is normally seen in subtle shades of grey or gold. But small, measurable color differences have been greatly exaggerated to make this telescopic, multicolored, moonscape captured during the Moon's full phase. The different colors are recognized to correspond to real differences in the chemical makeup of the lunar surface. Blue hues reveal titanium rich areas while orange and purple colors show regions relatively poor in titanium and iron. The familiar Sea of Tranquility, or Mare Tranquillitatis, is the blue area toward the upper right. White lines radiate across the orange-hued southern lunar highlands from 85-kilometer wide ray-crater Tycho at bottom right. The full moon that occurred earlier this month could be counted as a seasonal blue moon because it was, unusually, the third of four full moons to occur during northern summer (and hence southern winter). The featured 272-image composite demonstrates that the full Moon is always blue, but usually not blue enough in hue to ooh. Almost Hyperspace: Random APOD Generator  

Three Clusters in Puppis - 2022-02-18

Galactic or open star clusters are young. The swarms of stars are born together near the plane of the Milky Way, but their numbers steadily dwindle as cluster members are ejected by galactic tides and gravitational interactions. Caught in this telescopic frame over three degrees across are three good examples of galactic star clusters, seen toward the southern sky's nautical constellation Puppis. Below and left, M46 is some 5,500 light-years in the distance. Right of center M47 is only 1,600 light-years away and NGC 2423 (top) is about 2500 light-years distant. Around 300 million years young M46 contains a few hundred stars in a region about 30 light-years across. Sharp eyes can spot a planetary nebula, NGC 2438, at about 11 o'clock against the M46 cluster stars. But that nebula's central star is billions of years old, and NGC 2438 is likely a foreground object only by chance along the line of sight to youthful M46. Even younger, aged around 80 million years, M47 is a smaller and looser star cluster spanning about 10 light-years. Star cluster NGC 2423 is pushing about 750 million years in age though. NGC 2423 is known to harbor an extrasolar planet, detected orbiting one of its red giant stars.  

Super Moon vs. Micro Moon - 2012-11-29

Did you see the big, bright, beautiful Full Moon Wednesday night? That was actually a Micro Moon! On that night, the smallest Full Moon of 2012 reached its full phase only about 4 hours before apogee, the most distant point from Earth in the Moon's elliptical orbit. Of course, earlier this year on May 6, a Full Super Moon was near perigee, the closest point in its orbit. The relative apparent size of November 28's Micro Moon (right) is compared to the famous May 6 Super Moon in these two panels, matching telescopic images from Bucharest, Romania. The difference in apparent size represents a difference in distance of just under 50,000 kilometers between apogee and perigee, given the Moon's average distance of about 385,000 kilometers. How long do you have to wait to see another Full Micro Moon? Until January 16, 2014, when the lunar full phase will occur within about 3 hours of apogee.  

M17: The Omega Nebula - 1999-01-26

The Omega Nebula contains glowing gas, dark dust, and some unusually massive stars. Also known as the M17 and the Swan Nebula, the Omega Nebula is about 5000 light-years away, 20 light-years across, and visible with binoculars in the constellation of Sagittarius. A recent epoch of star formation has created some very massive stars that haven't yet had time to self-destruct. Until then, these stars appear very bright and emit light so energetic it breaks up the surrounding gas and dust. The streaks across the bright stars are blemishes caused by the digital camera.