XMM Launched
21.12.1999

X-ray astronomy entered a golden age earlier this month with the successful launch of the X-ray Multi-Mirror (XMM) satellite. XMM's three huge telescope barrels each hold 58 concentric cylindrical mirrors, together totaling a surface area rivaling a tennis court.

APOD: 2025 August 31 Б NGC 7027: The Pillow Planetary Nebula
31.08.2025

What created this unusual planetary nebula? Dubbed the Pillow Nebula and the Flying Carpet Nebula, NGC 7027 is one of the smallest, brightest, and most unusually shaped planetary nebulas known. Given its expansion rate, NGC 7027 first started expanding, as visible from Earth, about 600 years ago.

Sunspot Metamorphosis: From Bottom to Top
16.02.2005

Sunspots -- magnets the size of the Earth -- are normally seen flat on the Sun. The above digital metamorphosis, however, shows a sunspot as it appears at increasing heights, effectively in three dimensions. The above...

A Nearby Supernova in M51
19.07.2005

One of the nearest supernovas of recent years was discovered late last month in the bright nearby galaxy M51. It is visible on the right of the above before and after images of the picturesque spiral. Can you spot it?

M63: The Sunflower Galaxy from Hubble
9.11.2016

One of the bright spiral galaxies visible in the north sky is M63, the Sunflower Galaxy. M63, also catalogued as NGC 5055, can be found with a small telescope toward the constellation of Hunting Dogs (Canes Venatici).

Composite Messier 20 and 21
28.06.2017

The beautiful Trifid Nebula, also known as Messier 20, lies about 5,000 light-years away, a colorful study in cosmic contrasts. It shares this nearly 1 degree wide field with open star cluster Messier 21 (top left).

APOD: 2025 June 24 Б In the Center of Spiral Galaxy M61
24.06.2025

Is there a spiral galaxy in the center of this spiral galaxy? Sort of. Image data from the Hubble Space Telescope, the European Southern Observatory, and smaller telescopes on planet Earth are combined in this detailed portrait of face-on spiral galaxy Messier 61 (M61) and its bright center.

APOD: 2025 October 26 Б Halloween and the Ghost Head Nebula
26.10.2025

Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere).

Startling Star V838 Mon
5.12.2003

Variable star V838 Monocerotis startled astronomers in January of 2002, undergoing a dramatic outburst like no other variable star known. Followed closely by ground-based instruments and the Hubble Space Telescope over the following months...

Celebrating Hubble With NGC 6751
16.04.2005

Planetary nebulae can look simple, round, and planet-like in small telescopes. But images from the orbiting Hubble Space Telescope have become well known for showing these fluorescent gas shrouds of dying Sun-like stars to possess a staggering variety of detailed symmetries and shapes.