Mercurys Transit: An Unusual Spot on the Sun
7.05.2016

What's that dot on the Sun? If you look closely, it is almost perfectly round. The dot is the result of an unusual type of solar eclipse that occurred in 2006. Usually it is the Earth's Moon that eclipses the Sun. This time, the planet Mercury took a turn.

A Skygazers Full Moon
12.01.2000

This dramatically sharp picture of the full moon was recorded on 22 December, 1999 by astroimager Rob Gendler. Big, beautiful, bright, and evocative, it was the last full moon of the Y1.9Ks, pleasing and inspiring even casual skygazers.

Eclipsed Moon in the Morning
9.12.2011

Tomorrow, December 10, the Full Moon will slide through planet Earth's shadow in a total lunar eclipse. The entire eclipse sequence, including 51 minutes of totality, will be visible from Asia and Australia...

APOD: 2025 April 30 Б A Happy Sky over Bufa Hill in Mexico
29.04.2025

Sometimes, the sky itself seems to smile. A few days ago, visible over much of the world, an unusual superposition of our Moon with the planets Venus and Saturn created just such an iconic facial expression.

Lunation Matrix
30.09.2022

Observe the Moon every night and you'll see its visible sunlit portion gradually change. In phases progressing from New Moon to Full Moon to New Moon again, a lunar cycle or lunation is completed in about 29.5 days.

The Umbra of Earth
15.12.2011

The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, it has a circular cross section most easily seen during a lunar eclipse. For example, last Saturday the Full Moon slid across the southern half of Earth's umbral shadow, entertaining moonwatchers around much of the planet.

Find the New Moon
24.07.2022

Can you find the Moon? This usually simple task can be quite difficult. Even though the Moon is above your horizon half of the time, its phase can be anything from crescent to full.

Moonrise and Mountain Shadow
13.03.2020

What phase of the Moon is 3.14 radians from the Sun? The Full Moon, of course. Even though the Moon might look full for several days, the Moon is truly at its full phase when it is 3.14 radians (aka 180 degrees) from the Sun in ecliptic longitude.

Crescent Neptune and Triton
26.05.2023

Gliding through the outer Solar System, in 1989 the Voyager 2 spacecraft looked toward the Sun to find this view of most distant planet Neptune and its moon Triton together in a crescent phase. The elegant image of ice-giant planet and largest moon was taken from behind just after Voyager's closest approach.

Ring of Fire over Easter Island
10.10.2024

The second solar eclipse of 2024 began in the Pacific. On October 2nd the Moon's shadow swept from west to east, with an annular eclipse visible along a narrow antumbral shadow path tracking...