Astronomy Picture Of the Day (APOD)Geminid Meteors over Chile
Are meteors streaming out from a point in the sky? Yes, in a way. When the Earth crosses a stream of Sun-orbiting meteors, these meteors appear to come from the direction of the stream -- with the directional point called the radiant.
Lines of Time
In time stars trace lines through the night sky on a rotating planet. Taken over two hours or more, these digitally added consecutive exposures were made with a camera and wide angle lens fixed to a tripod near Orel farm, Primorsky Krai, Russia, planet Earth.
Pleiades to Hyades
This cosmic vista stretches almost 20 degrees from top to bottom, across the dusty constellation Taurus. It begins at the Pleiades and ends at the Hyades, two star clusters recognized since antiquity in Earth's night sky. At top, the compact Pleiades star cluster is about 400 light-years away.
Spiral Galaxy NGC 6744
Beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo and appears as only a faint, extended object in small telescopes.
It may appear, at first, like the Galaxy is producing the lightning, but really it's the Earth. The featured nighttime landscape was taken from a southern tip of the Italian Island of Sardinia in early June.
M27: The Dumbbell Nebula
Is this what will become of our Sun? Quite possibly. The first hint of our Sun's future was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of diffuse objects not to be confused with comets.
Mercury Crosses a Quiet Sun
What's that black dot crossing the Sun? The planet Mercury. Mercury usually passes over or under the Sun, as seen from Earth, but last month the Solar System's innermost planet appeared to go just about straight across the middle.
Starburst Galaxy M94 from Hubble
Why does this galaxy have a ring of bright blue stars? Beautiful island universe Messier 94 lies a mere 15 million light-years distant in the northern constellation of the Hunting Dogs (Canes Venatici).
Star Trails for a Red Planet
Does Mars have a north star? In long exposures of Earth's night sky, star trails make concentric arcs around the north celestial pole, the direction of our fair planet's axis of rotation. Bright star Polaris is presently the Earth's North Star, close on the sky to Earth's north celestial pole.
Galileo s Europa Remastered
Looping through the Jovian system in the late 1990s, the Galileo spacecraft recorded stunning views of Europa and uncovered evidence that the moon's icy surface likely hides a deep, global ocean. Galileo...