APOD: 2026 February 11 Б A Year of Sunspots
11.02.2026

How many sunspots can you see? The central image shows the many sunspots that occurred in 2025, month by month around the circle, and all together in the grand central image. Each sunspot is magnetically cooled and so appears dark -- and can last from days to months.

Abell 370: Galaxy Cluster Gravitational Lens
19.03.2019

What are those strange arcs? While imaging the cluster of galaxies Abell 370, astronomers noticed an unusual arc. The arc wasn't understood right away -- not until better images showed that...

APOD: 2026 June 28 Б AR 4478: Giant Sunspot Group
28.06.2026

Right now, one of the largest sunspot groups in recent history is crossing the Sun. Active Region 4478 is not only big -- it's violent, showing tangled magnetic fields capable of throwing off huge clouds of particles into the Solar System. Some of these CMEs might impact the Earth.

The Magnetic Field of the Whirlpool Galaxy
20.01.2021

Do magnetic fields always flow along spiral arms? Our face-on view of the Whirlpool Galaxy (M51) allows a spectacularly clear view of the spiral wave pattern in a disk-shaped galaxy. When observed with a radio telescope, the magnetic field appears to trace the arms' curvature.

Welcome to the Moon Hotel
13.07.2001

The most detailed proposal so far for a hotel and resort destination on the Moon (!) has been prepared by Dutch architect Hans-Jurgen Rombaut. The harsh lunar environment posed serious design challenges but the Moon...

Galaxy Cluster Lenses Farthest Known Galaxy
17.02.2004

Gravity can bend light, allowing whole clusters of galaxies to act as huge telescopes. Almost all of the bright objects in this just-released Hubble Space Telescope image are galaxies in the cluster known as Abell 2218.

Launch of the Parker Solar Probe
15.08.2018

When is the best time to launch a probe to the Sun? The now historic answer -- which is not a joke because this really happened this past weekend -- was at night. Night, not only...

Giant Cluster Bends, Breaks Images
14.06.1998

What are those strange blue objects? Many are images of a single, unusual, beaded, blue, ring-like galaxy which just happens to line-up behind a giant cluster of galaxies. Cluster galaxies here appear yellow and -- together with the cluster's dark matter -- act as a gravitational lens.

Giant Cluster Bends, Breaks Galaxy Images
3.05.1997

What are those strange blue objects? Many are images of a single, unusual, beaded, blue, ring-like galaxy which just happens to line-up behind a giant cluster of galaxies. Cluster galaxies here appear yellow and -- together with the cluster's dark matter -- act as a gravitational lens.

Stereo Eros
13.02.2021

Get out your red/blue glasses and float next to asteroid 433 Eros. Orbiting the Sun once every 1.8 years, the near-Earth asteroid is named for the Greek god of love. Still, its shape more closely resembles a lumpy potato than a heart.