The Case of the Missing Supernova
13.04.1999

Would you notice a second Moon in the sky? About 700 years ago, light from a tremendous explosion reached Earth that should have appeared almost as bright as a full Moon. The bright spot should have lasted for weeks, yet no notation of such an occurrence has been found in historical records.

Moonrise Over Turkey
16.06.2009

Is the Moon larger when near the horizon? No -- as shown above, the Moon appears to be very nearly the same size no matter its location on the sky. Oddly, the cause or causes for the common Moon Illusion are still being debated.

APOD: 2023 April 25 Б Northern Lights over Southern Europe
25.04.2023

Did you see an aurora over the past two nights? Many people who don't live in Earth's far north did. Reports of aurora came in not only from northern locales in the USA as Alaska, but as far south as Texas and Arizona. A huge auroral oval extended over Europe and Asia, too.

APOD: 2025 June 2 Б Veil Nebula: Wisps of an Ancient Supernova
2.06.2025

Wisps like this are all that remain visible of a Milky Way star. About 7,000 years ago that star exploded in a supernova, leaving the Veil Nebula. At the time, the expanding cloud was likely as bright as a crescent Moon, remaining visible for weeks to people living at the dawn of recorded history.

Cas A Supernova Remnant in X Rays
3.01.2000

The complex shell of a star seen to explode 300 years ago is helping astronomers to understand how that star exploded. The above recently released image of supernova remnant Cassiopeia A (Cas A) shows unprecedented detail in three X-ray colors.

Veil Nebula: Wisps of an Exploded Star
19.09.2017

Wisps like this are all that remain visible of a Milky Way star. About 7,000 years ago that star exploded in a supernova leaving the Veil Nebula. At the time, the expanding cloud was likely as bright as a crescent Moon, remaining visible for weeks to people living at the dawn of recorded history.

APOD: 2024 January 24 Б Earth and Moon from Beyond
24.01.2024

What do the Earth and Moon look like from beyond the Moon? Although frequently photographed together, the familiar duo was captured with this unusual perspective in late 2022 by the robotic Orion spacecraft of NASA's Artemis I mission as it looped around Earth's most massive satellite and looked back toward its home world.

Zodiacal Light and the False Dawn
12.09.2001

An unusual triangle of light will be particularly bright near the eastern horizon before sunrise during the next two months for observers in Earth's northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles.

Zodiacal Light and the False Dawn
25.08.2004

An unusual triangle of light will be particularly bright near the eastern horizon before sunrise during the next two months for observers in Earth's northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles.

Airplane Flight Patterns over the USA
29.04.2008

What are these Earthlings going? Millions of people move about planet Earth by airplane every day. Hundreds of thousands of airplane flights take place over the US every day. A dramatic graphical depiction of these flights was created by Aaron Koblin and is shown above.