Astronomy Picture Of The Day

Sometimes, the Moon visits the Pleiades. Technically, this means that the orbit of our Moon takes it directly in front of the famous Pleiades star cluster, which is far in the distance. The technical term for the event is an occultation, and the Moon is famous for its rare occultations of all planets and several well-known […]

How much mass do flocculent spirals hide? The featured image of flocculent spiral galaxy NGC 4414 was taken with the Hubble Space Telescope to help answer this question. Flocculent spirals — galaxies without well-defined spiral arms — are a quite common form of galaxy, and NGC 4414 is one of the closest. Stars and gas near […]

Why are there so many moonquakes? Analyses of seismometers left on the moon during the Apollo moon landings reveal a surprising number of moonquakes occurring within 100 kilometers of the surface. In fact, 62 moonquakes were detected in data recorded between 1972 and 1977. Many of these moonquakes are not only strong enough to move furniture […]

In dramatic silhouette against a cloudy daytime sky over Paris, France, gargoyles cast their monstrous gaze outward from the west façade of Notre Dame Cathedral. Taken on March 29, this telephoto snapshot also captures the dramatic silhouette of a New Moon against the  right solar disk in a partial solar eclipse. Happening high in Parisian […]

Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups. The four prominent galaxies seen in this intriguing telescopic skyscape are one such group, Hickson 44. The galaxy group is about 100 million light-years distant, far beyond the spiky foreground Milky Way stars, […]

A 26 hour old Moon poses behind the craggy outline of the Italian Dolomites in this twilight mountain and skyscape. The one second long exposure was captured near moonset on March 30. And while only a a sliver of its sunlit surface is visible, most of the Moon’s disk can be seen by earthshine as […]

Why does Jupiter have rings? Jupiter’s main ring was discovered in 1979 by NASA’s passing Voyager 1  spacecraft, but its origin was then a mystery. Data from NASA’s Galileo spacecraft that orbited Jupiter from 1995 to 2003, however, confirmed the hypothesis that this ring was created by meteoroid impacts on small nearby moons. As a small meteoroid […]

Can the Sun appear to rise twice at the same time? This was just the case a few days ago as our Solar System’s bright central orb rose just as it was being partially eclipsed by the Moon. The featured video shows this unusual double-sunrise in real time and being reflected by the St. Lawrence River. Soon after […]

If you watch long enough, a comet will appear. Before then, you will see our Solar System from inside the orbit of Mercury as recorded by NASA‘s Parker Solar Probe looping around the Sun. The video captures coronal streamers into the solar wind, a small Coronal Mass Ejection, and planets including, in order of appearance, […]

Get out your red/blue glasses and float next to Helene, small, icy moon of Saturn. Appropriately named, Helene is a Trojan moon, so called because it orbits at a Lagrange point. A Lagrange point is a gravitationally stable position near two massive bodies, in this case Saturn and larger moon Dione. In fact, irregularly shaped ( […]

Why is the Moon so dusty? On Earth, rocks are weathered by wind and water, creating soil and sand. On the Moon, eons of constant micrometeorite bombardment have blasted away at the rocky surface creating a layer of powdery lunar soil or regolith. For the Apollo astronauts and their equipment, the pervasive, fine, gritty dust […]

One of the brightest galaxies in planet Earth’s sky is similar in size  to our Milky Way Galaxy: big beautiful Messier 81. Also known as NGC 3031 or Bode’s galaxy for its 18th century discoverer, this grand spiral can be found toward the northern constellation of Ursa Major, the Great Bear. The sharp, detailed telescopic view reveals […]