Cylindrical Mountains on Venus
16.10.2016

What could cause a huge cylindrical mountain to rise from the surface of Venus? Such features that occur on Venus are known as coronas. Pictured here in the foreground is 500-kilometer wide Atete Corona found in a region of Venus known as the Galindo.

Close Mars
31.08.2018

Still bright in evening skies, Mars was just past opposition and closest to Earth on July 31, a mere 57.6 million kilometers away. Captured only a week later, this remarkable image shows...

M78 Wide Field
21.01.2021

Interstellar dust clouds and glowing nebulae abound in the fertile constellation of Orion. One of the brightest, M78, is centered in this colorful, wide field view, covering an area north of Orion's belt. At a distance of about 1,500 light-years, the bluish reflection nebula is around 5 light-years across.

Messier 4
29.11.2024

Messier 4 can be found west of bright red-giant star Antares, alpha star of the constellation Scorpius. M4 itself is only just visible from dark sky locations, even though the globular cluster of 100,000 stars or so is a mere 5,500 light-years away.

APOD: 2024 December 18 Б NGC 660: Polar Ring Galaxy
18.12.2024

What kind of strange galaxy is this? This rare structure is known as a polar ring galaxy, and it seems to have two different rings of stars. In this galaxy, NGC 660, one ring...

Heaven on Earth
6.11.2000

If sometimes it appears that the entire Milky Way Galaxy is raining down on your head, do not despair. It happens twice a day. As the Sun rises in the East, wonders of the night sky become less bright than the sunlight scattered by our own Earth's atmosphere, and so fade from view.

Mysterious Black Water in Florida Bay
2.04.2002

What is causing the water in Florida Bay to turn black? The mysterious black color could be seen as early as last December in images taken by the SeaWIFS instrument on board the Earth-orbiting SeaStar satellite.

Europa's Surface
13.08.1996

Voyager spacecraft images of Europa's surface, like the one above, are suggestive of sea ice on Earth. The criss-crossing dark streaks may indeed be cracks in its ice-covered surface caused by Jupiter's tidal stresses accompanied by the freezing and expansion of an underlying layer of water.

Dusting Spiral Galaxies
16.01.1998

How much dust is in spiral galaxies? Does it block out much of the starlight? Because astronomers rely on an accurate knowledge of galaxy properties to investigate a wide range of problems, like galaxy and quasar evolution and the nature of dark matter, answers to simple questions like this are key.

Moon Occults Saturn
8.05.1999

On September 18, 1997, many stargazers in the U. S. were able to watch a lovely early morning lunar occultation as a bright Moon passed in front of Saturn. Using a 1.2 meter reflector, astronomer Kris Stanek had an excellent view of this dream-like event from the Whipple Observatory atop Arizona's Mount Hopkins.