dark energy slivers

2026 May 9

Messier Craters in Stereo Image Credit: Apollo 11, NASA; Stereo Image Copyright Patrick Vantuyne

Explanation: Many bright nebulae and star clusters in planet Earth’s sky are associated with the name of astronomer Charles Messier from his famous 18th century catalog. His name is also given to these two large and remarkable craters on the Moon. Standouts in the dark, smooth lunar Sea of Fertility or Mare Fecunditatis, Messier (left) and Messier A have dimensions of 15 by 8 and 16 by 11 kilometers respectively. Their elongated shapes are explained by the extremely shallow-angle trajectory followed by an impactor, moving left to right, that gouged out the craters. The shallow impact also resulted in two bright rays of material extending along the surface to the right, beyond the picture. Intended to be viewed with red/blue glasses (red for the left eye), this striking stereo picture of the crater pair was recently created from high resolution scans of two images (AS11-42-6304, AS11-42-6305) taken during the Apollo 11 mission to the Moon.

2026 June 1

Saturn at Night Image Credit: NASA, JPL-Caltech, Space Science Institute, Mindaugas Macijauskas

Explanation: Telescopic views of Saturn and its beautiful rings often make it the star of star parties. But this stunning view of the outer gas gaint planet’s rings and night side just isn’t possible from telescopes in the vicinity of planet Earth. Peering out from the inner Solar System they can only bring Saturn’s day side into view. In fact, this image of Saturn’s slender sunlit crescent with the planet’s night shadow cast across its broad and complex ring system was captured by the robot spacecraft Cassini. After a seven year long journey from planet Earth, Cassini called Saturn orbit home for 13 years (from 2004 - 2017) before it was directed to dive into the atmosphere of the gas giant on September 15, 2017. This magnificent mosaic is composed of frames recorded by Cassini’s wide-angle camera only two days before its grand final plunge. And Saturn’s night will not be seen again until another spaceship from Earth calls.

2025 October 4

The Rotating Moon Video Credit: NASA, Lunar Reconnaissance Orbiter, Arizona State U.

Explanation: No one on Earth sees the Moon rotate like this. That’s because the Moon is tidally locked in synchronous rotation, showing only one side to denizens of our fair planet. Still, given modern digital technology, combined with many detailed images returned by the Lunar Reconnaissance Orbiter (LRO), a high resolution virtual Moon rotation movie can be composed. In fact, the featured time-lapse video starts with a view of the familiar lunar nearside and quickly finds the Mare Orientale, a large crater with a dark center that is difficult to see from the Earth, rotating into view just below the equator. In a complete lunar rotation condensed into 24 seconds, the video clearly shows that the Earth-facing nearside of the Moon contains an abundance of dark lunar maria, while the lunar farside is dominated by bright lunar highlands. Of course, you can just join other moon-watchers under hopefully clear skies tonight. Check out the sunlit portion of the lunar nearside on International Observe the Moon Night.