Astronomy Picture Of the Day (APOD)Noctilucent Clouds over Paris
It's northern noctilucent cloud season. Composed of small ice crystals forming only during specific conditions in the upper atmosphere, noctilucent clouds may become visible at sunset during late summer when illuminated by sunlight from below. Noctilucent clouds are the highest clouds known and now established to be polar mesospheric clouds observed from the ground.
Andromeda over the Sahara Desert
What is the oldest thing you can see? At 2.5 million light years distant, the answer for the unaided eye is the Andromeda galaxy, because its photons are 2.5 million years old when they reach you.
In the Center of the Cats Eye Nebula
Three thousand light-years away, a dying star throws off shells of glowing gas. This image from the Hubble Space Telescope reveals the Cat's Eye Nebula (NGC 6543), to be one of the most complex planetary nebulae known.
Saturn and ISS
Soaring high in skies around planet Earth, bright planet Saturn was a star of June's morning planet parade. But very briefly on June 24 it posed with a bright object in low Earth orbit, the International Space Station.
Roots on a Rotating Planet
With roots on a rotating planet, an old tree is centered in this sequence of 137 exposures each 20 seconds long, recorded one night from northern Sicily. Digital camera and fisheye lens were fixed to a tripod to capture the dramatic timelapse, so the stars trailed through the region's dark sky.
The NGC 6914 Complex
A study in contrasts, this colorful skyscape features stars, dust, and glowing gas in the vicinity of NGC 6914. The interstellar complex of nebulae lies some 6,000 light-years away, toward the high-flying northern constellation Cygnus and the plane of our Milky Way Galaxy.
Milky Way Motion in 3D from Gaia
Our sky is alive with the streams of stars. The motions of 26 million Milky Way stars are evident in the featured map constructed from recent data taken by ESA's Gaia satellite. Stars colored blue are moving toward us, while red indicates away. Lines depict the motion of the stars across the sky.
A Molten Galaxy Einstein Ring Galaxy
It is difficult to hide a galaxy behind a cluster of galaxies. The closer cluster's gravity will act like a huge lens, pulling images of the distant galaxy around the sides and greatly distorting them. This is just the case observed in the featured image recently re-processed image from the Hubble Space Telescope.
Strawberry Supermoon Over Devils Saddle
Near the horizon the full moon often seems to loom large, swollen in appearance by the famous Moon illusion. But time-lapse image sequences demonstrate that the Moon's angular size doesn't really change as it rises or sets. Its color does, though.
Phobos: Doomed Moon of Mars
This moon is doomed. Mars, the red planet named for the Roman god of war, has two tiny moons, Phobos and Deimos, whose names are derived from the Greek for Fear and Panic. These...