Crescent Moon and Venus
6.03.2009

Last Friday, the Moon and Venus shared the early evening sky in a beautiful conjunction. Separated by only about 2 degrees, they also were both in a crescent phase. Just like our Moon, Venus can appear as a full disk or a thin crescent.

Moon Pi and Mountain Shadow
14.03.2025

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 Pi radians (aka 180 degrees) from the Sun in ecliptic longitude.

Sunshine, Earthshine
19.03.2015

Today's date marks an Equinox and a New Moon. Remarkably, while the exact timing of both geocentric events occur within a span of only 13 hours, the moon also reaches its new phase only 14 hours after perigee, the closest point in its orbit.

Moon Pairs and the Synodic Month
26.09.2020

Observe the Moon each night and its visible sunlit portion will gradually change. In phases progressing from New Moon to Full Moon to New Moon again, a lunar cycle or synodic month is completed in about 29.5 days.

Mercurys Transit: An Unusual Spot on the Sun
24.08.2014

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 Crescent Sunrise
17.08.1999

Normally, the Moon shows phases, but the Sun does not. The reason is founded in the fact that the Moon shines only by reflected sunlight. When the Moon is closer to the Sun than the Earth, only part of it appears to be lit - resulting in a familiar crescent-shaped phase.

Embraced by Sunlight
3.02.2022

Even though Venus (left) was the brightest planet in the sky it was less than 1/30th the apparent size of the Moon on January 29. But as both rose before the Sun they shared a crescent phase.

Mercurys Transit: An Unusual Spot on the Sun
14.11.2006

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 last week. Usually it is the Earth's Moon that eclipses the Sun.

A Rare Annular Venusian Solar Eclipse
15.06.2004

An unusual type of solar eclipse occurred last week. Usually it is the Earth's Moon that eclipses the Sun. Last week, for the first time in over 100 years, the planet Venus took a turn.

Crescent Venus and Moon
16.05.2010

There's something behind these clouds. Those faint graceful arcs, upon inspection, are actually far, far in the distance. They are the Earth's Moon and the planet Venus. Both the Moon and Venus are bright enough to be seen during the day, and both are quite capable of showing a crescent phase.