The Observable UniverseHow far can you see? Everything you can see, and everything you could possibly see, right now, assuming your eyes could detect all types of radiations around you — is the observable universe. In light, the farthest we can see comes from the cosmic microwave background, a time 13.8 billion years ago when the universe was…Read More

Dione and Rhea Ring TransitSeen to the left of Saturn’s banded planetary disk, small icy moons Dione and Rhea are caught passing in front of the gas giant’s extensive ring system in this sharp telescopic snapshot. The remarkable image was recorded on November 20, when Saturn’s rings were nearly edge-on when viewed from planet Earth. In fact, every…Read More

3I/ATLAS: A View from Planet EarthNow outbound after its perihelion or closest approach to the Sun on October 29, Comet 3I/ATLAS is only the third known interstellar object to pass through our fair Solar System. Its greenish coma and faint tails are seen against a background of stars in the constellation Virgo in this view from planet Earth,…Read More

Alnitak, Alnilam, MintakaAlnitak, Alnilam, and Mintaka are the bright bluish stars from east to west (upper right to lower left) along the diagonal in this cosmic vista. Otherwise known as the Belt of Orion, these three blue supergiant stars are hotter and much more massive than the Sun. They lie from 700 to 2,000 light-years away, born of Orion’s…Read More

Chamaeleon Dark NebulasSometimes the dark dust of interstellar space has an angular elegance. Such is the case toward the far-south constellation of Chamaeleon. Normally too faint to see, dark dust is best known for blocking visible light from stars and galaxies behind it. In this 11.4-hour exposure, however, the dust is seen mostly in light of…Read More