The Ecliptic Plane
29.05.1999

The Plane of the Ecliptic is illustrated in this Clementine star tracker camera image which reveals (from right to left) the Moon lit by Earthshine, the Sun's corona rising over the Moon's dark limb, and the planets Saturn, Mars, and Mercury.

The Ecliptic Plane
14.10.2000

The Plane of the Ecliptic is well illustrated in this picture from the 1994 lunar prospecting Clementine spacecraft. Clementine's star tracker camera image reveals (from right to left) the Moon lit by Earthshine, the Sun's corona rising over the Moon's dark limb, and the planets Saturn, Mars, and Mercury.

Perseids from Perseus
9.08.2020

Where are all these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Perseus. That is why the meteor shower that peaks tomorrow night is known as the Perseids -- the meteors all appear to came from a radiant toward Perseus.

Colorful Airglow Bands Surround Milky Way
12.03.2022

Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere.

Colorful Airglow Bands Surround Milky Way
5.03.2018

Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere.

Satellites Behind Pinnacles
13.06.2022

What are all those streaks across the background? Satellite trails. First, the foreground features picturesque rock mounds known as Pinnacles. Found in the Nambung National Park in Western Australia, these human-sized spires are made by unknown processes from ancient sea shells (limestone). Perhaps more eye-catching, though, is the sky behind.

Planck Maps the Microwave Background
21.07.2018

What is our universe made of? To help find out, ESA launched the Planck satellite from 2009 to 2013 to map, in unprecedented detail, slight temperature differences on the oldest optical surface known -- the background sky when our universe first became transparent to light.

Rainbow Airglow over the Azores
17.04.2021

Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere.

Rainbow Airglow over the Azores
21.03.2016

Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere.

APOD: 2025 June 3 Б Rainbow Airglow over the Azores
2.06.2025

Why would the sky glow like a giant repeating rainbow? Airglow. Now, air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere.