Stellar Spectral Types: OBAFGKM
18.04.2004

Astronomers divide stars into different spectral types. First started in the 1800s, the spectral type was originally meant to classify the strength of hydrogen absorption lines. A few types that best describe the temperature of the star remain in use today.

Cat s Eye
10.09.2004

Staring across interstellar space, the alluring Cat's Eye nebula lies three thousand light-years from Earth. A classic planetary nebula, the Cat's Eye (NGC 6543) represents a final, brief yet glorious phase in the life of a sun-like star.

Irregular Galaxy NGC 55
10.10.2008

Irregular galaxy NGC 55 is thought to be similar to the Large Magellanic Cloud (LMC). But while the LMC is about 180,000 light-years away and is a well known satellite of our own Milky Way Galaxy, NGC 55 is more like 6 million light-years distant and is a member of the Sculptor Galaxy Group.

M39: Open Cluster in Cygnus
12.04.2009

Lying just at the limit of human perception is a picturesque starfield containing one of the larger open clusters on the northern sky. Spanning an angle larger than the Moon, M39's relatively few stars lie only about 800 light years distant toward the constellation of Cygnus.

Nearby Spiral Galaxy NGC 4945
27.05.2015

Large spiral galaxy NGC 4945 is seen edge-on near the center of this cosmic galaxy portrait. In fact, NGC 4945 is almost the size of our own Milky Way Galaxy. Its own dusty disk, young blue star clusters, and pink star forming regions standout in the sharp, colorful telescopic image.

The Tulip in the Swan
19.10.2016

Framing a bright emission region this telescopic view looks out along the plane of our Milky Way Galaxy toward the nebula rich constellation Cygnus the Swan. Popularly called the Tulip Nebula, the glowing cloud of interstellar gas and dust is also found in the 1959 catalog by astronomer Stewart Sharpless as Sh2-101.

Black Hole Accreting with Jet
26.03.2017

What happens when a black hole devours a star? Many details remain unknown, but recent observations are providing new clues. In 2014, a powerful explosion was recorded by the ground-based robotic telescopes of the All Sky Automated Survey for SuperNovae (ASAS-SN) project, and followed up by instruments including NASA's Earth-orbiting Swift satellite.

APOD: 2023 July 12 Б Rings and Bar of Spiral Galaxy NGC 1398
11.07.2023

Why do some spiral galaxies have a ring around the center? Spiral galaxy NGC 1398 not only has a ring of pearly stars, gas and dust around its center, but a bar of stars and gas across its center, and spiral arms that appear like ribbons farther out.

APOD: 2024 April 28 Б Rings Around the Ring Nebula
27.04.2024

The Ring Nebula (M57) is more complicated than it appears through a small telescope. The easily visible central ring is about one light-year across, but this remarkably deep exposure - a collaborative effort combining data from three different large telescopes - explores the looping filaments of glowing gas extending much farther from the nebula's central star.

APOD: 2025 June 30 Б NGC 4651: The Umbrella Galaxy
29.06.2025

It's raining stars. What appears to be a giant cosmic umbrella is now known to be a tidal stream of stars stripped from a small satellite galaxy. The main galaxy, spiral galaxy...