Solar Flare from a Sharper Sun
21.11.2014

Solar active region AR2192 was the largest recorded sunspot group of the last 24 years. Before rotating off the Earth-facing side of the Sun at the end of October, it produced a whopping six energetic X-class flares.

Comet Churyumov Gerasimenko in Crescent
28.04.2015

What's happening to Comet 67P/ChuryumovGerasimenko? As the 3-km wide comet moves closer to the Sun, heat causes the nucleus to expel gas and dust. The Rosetta spacecraft arrived at the comet's craggily double nucleus last July and now is co-orbiting the Sun with the giant dark iceberg.

The Sun in X rays from NuSTAR
28.12.2014

Why are the regions above sunspots so hot? Sunspots themselves are a bit cooler than the surrounding solar surface because the magnetic fields that create them reduce convective heating. It is therefore unusual that regions overhead -- even much higher up in the Sun's corona -- can be hundreds of times hotter.

Planetary Nebula Mz3: The Ant Nebula
25.04.2015

Why isn't this ant a big sphere? Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round. Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round?

The Horsehead Nebula
26.12.2017

One of the most identifiable nebulae in the sky, the Horsehead Nebula in Orion, is part of a large, dark, molecular cloud. Also known as Barnard 33, the unusual shape was first discovered on a photographic plate in the late 1800s.

APOD: 2024 May 26 Б A Solar Filament Erupts
25.05.2024

What's happened to our Sun? Nothing very unusual -- it just threw a filament. Toward the middle of 2012, a long standing solar filament suddenly erupted into space, producing an energetic coronal mass ejection (CME).

Voyager at 90 AU
19.11.2003

Launched in 1977, Voyager 1 is now about 12 light-hours or 90 astronomical units (AU) from the Sun, making this spacecraft humanity's most distant ambassador to the cosmos. Well beyond the orbits...

The Horsehead Nebula from Blue to Infrared
28.07.2014

One of the most identifiable nebulae in the sky, the Horsehead Nebula in Orion, is part of a large, dark, molecular cloud. Also known as Barnard 33, the unusual shape was first discovered on a photographic plate in the late 1800s.

APOD: 2023 May 16 Б Total Eclipse: The Big Corona
15.05.2023

Most photographs don't adequately portray the magnificence of the Sun's corona. Seeing the corona first-hand during a total solar eclipse is unparalleled. The human eye can adapt to see coronal features and extent that average cameras usually cannot. Welcome, however, to the digital age.

M87 s Energetic Jet
10.12.2004

An energetic jet from the core of giant elliptical galaxy M87 stretches outward for 5,000 light-years. This monstrous jet appears in the panels above to be a knotted and irregular structure, detected across the spectrum, from x-ray to optical to radio wavelengths.