APOD: 2025 September 18 Б Comet C/2025 R2 SWAN
18.09.2025

A new visitor from the outer Solar System, comet C/2025 R2 (SWAN) also known as SWAN25B was only discovered late last week, on September 11. That's just day before the comet reached perihelion, its closest approach to the Sun.

Surrounded by Mars
18.09.2001

Just after landing on Mars in 1997, the robotic Mars Pathfinder main station took a quick first look around. This insurance panorama was taken even before the Sagan Memorial Station camera was raised to its two-meter-high perch. The full view is best seen by slowly scrolling to the right.

Milky Way Molecule Map
30.04.1997

Where are the Milky Way's gas clouds and where are they going? Stars form in gas clouds, and the motion of gas clouds tell us about the size and rotation speed of our own Milky Way Galaxy.

Big Mars from Hubble
27.08.2003

At about 10 am Universal Time today, Mars and Earth will pass closer than in nearly 60,000 years. Mars, noticeably red, will be the brightest object in the eastern sky just after sunset.

Canis Major Dwarf: A New Closest Galaxy
17.11.2003

What is the closest galaxy to the Milky Way? The new answer to this old question is the Canis Major dwarf galaxy. For many years astronomers thought the Large Magellan Cloud (LMC) was closest, but its title was supplanted in 1994 by the Sagittarius dwarf galaxy.

Comet C 2002 T7 (LINEAR)
22.04.2004

Discovered by the the Lincoln Near Earth Asteroid Research (LINEAR) project in October of 2002, comet C/2002 T7 is now visiting the inner solar system, making its closest approach (see animation by L. Koehn) to the Sun tomorrow, April 23rd.

NGC 6302: Big Bright Bug Nebula
5.05.2004

The bright clusters and nebulae of planet Earth's night sky are often named for flowers or insects, and NGC 6302 is no exception. With an estimated surface temperature of about 250,000 degrees...

Aurora Over Yellowknife
22.09.2009

Sometimes, after your eyes adapt to the dark, a spectacular sky appears. In this case, a picturesque lake lies in front of you, beautiful green auroras flap high above you, brilliant stars shine far in the distance, and a brilliant moon shines just ahead of you.

Sunspots and Silhouettes
4.07.2012

What stands between you and the Sun? Apparently, as viewed from Paris last week, one visible thing after another. First, in the foreground, is the Basilica of the Sacred Heart, built in the late 1800s and located on the highest hill in Paris, France.

Halo of the Cat s Eye
31.08.2012

The Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its haunting symmetries are seen in the very central region of this tantalizing image, processed to reveal the enormous but extremely faint halo of gaseous material, about 6 light-years across, which surrounds the brighter, familiar planetary nebula.