Bright Star Knots in NGC 4038
2.06.1997

This galaxy is having a bad millennium. In fact, the past 100 million years haven't been so good, and probably the next billion or so should be quite tumultuous. NGC 4039 was a normal spiral galaxy, minding its own business, when NGC 4038 crashed into it.

PG 1115: A Ghost of Lensing Past
2.11.1998

In this tangle of quasars and galaxies lies a clue to the expansion rate of the universe. A diffuse glow evident in the picture on the left reveals a normal elliptical galaxy. Directly behind this galaxy lies a normal quasar.

Ring Galaxy AM 0644 741 from Hubble
22.10.2005

How could a galaxy become shaped like a ring? The rim of the blue galaxy pictured on the right is an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars.

Makemake of the Outer Solar System
16.07.2008

Recently discovered Makemake is one of the largest objects known in the outer Solar System. Pronounced MAH-kay MAH-kay, this Kuiper belt object is only slightly smaller than Pluto, orbits the Sun only slightly further out than Pluto, and appears only slightly dimmer than Pluto.

Hammer Versus Feather on the Moon
1.11.2011

If you drop a hammer and a feather together, which reaches the ground first? On the Earth, it's the hammer, but is the reason only because of air resistance? Scientists even before Galileo have pondered and tested this simple experiment and felt that without air resistance, all objects would fall the same way.

NGC 1898: Globular Cluster in the LMC
3.10.2018

Jewels don't shine this bright -- only stars do. And almost every spot in this glittering jewel-box of an image from the Hubble Space Telescope is a star. Now some stars are more red than our Sun, and some more blue -- but all of them are much farther away.

Starburst Galaxy M94 from Hubble
31.07.2022

Why does this galaxy have a ring of bright blue stars? Beautiful island universe Messier 94 lies a mere 15 million light-years distant in the northern constellation of the Hunting Dogs (Canes Venatici).

APOD: 2023 May 23 Б Jupiters Swirls from Juno
23.05.2023

Big storms are different on Jupiter. On Earth, huge hurricanes and colossal cyclones are centered on regions of low pressure, but on Jupiter, it is the high-pressure, anti-cyclone storms that are the largest. On Earth, large storms can last weeks, but on Jupiter they can last years.

Stickney Crater
8.07.2023

Stickney Crater, the largest crater on the martian moon Phobos, is named for Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the Red Planet's moons in 1877.

APOD: 2025 June 10 Б Enceladus in True Color
10.06.2025

Do oceans under the ice of Saturn's moon Enceladus contain life? A reason to think so involves long features -- some dubbed tiger stripes -- that are known to be spewing ice from the moon's icy interior into space.