Credit: NASA/JPL-Caltech/Space Science Institute.
Monday, 23 March 2026
Saturn's fourth-largest moon, Dione, can be seen through the haze of the planet's largest moon, Titan, in this view of the two, taken by NASA's Cassini spacecraft on December 22, 2011, with the planet and its rings in the background. The north polar hood is visible on Titan here, appearing as a detached layer at the top of the moon.
This view looks toward the sides of Titan (5,150 kilometers across) and Dione (1,123 kilometers across), which are facing away from Saturn. North is up on the moons. This view looks toward the northern, sunlit side of the rings from just above the ring plane.
Credit: ESA's Mars Express / ESA / DLR / FU Berlin.
Tuesday, 24 March 2026
Lee waves are atmospheric gravity waves that form when stable air flows over significant topographic obstacles like mountains, volcanoes, or large crater rims. As the wind is forced upward by the terrain, it undergoes adiabatic cooling, causing water vapor or carbon dioxide to condense into visible, ripple-like clouds on the downwind (lee) side. They often appear as "cloud trains" or straight, parallel lines perpendicular to the wind direction.
Some can form "ship-wake" patterns or extend over 1,000 km downwind from large craters. Horizontal wavelengths typically range from 15 km to 50 km, though some massive volcanic structures, such as Arsia Mons, have reached 60 km. These waves are most common during Mars' northern fall and winter, when high near-surface stability and strong wind shear from the winter mid-latitude jet stream create ideal conditions for their formation.
Depending on the temperature and altitude (typically between 10 km and 55 km), these clouds can be composed of water ice crystals or CO2 ice. Recent high-cadence images from the Emirates Mars Mission (EMM) have even shown lee waves rapidly evolving into dust storm features within a single morning.
Credit: NASA, ESA, Dennis Bodewits (AU); Processing: Joseph DePasquale (STScI).
Wednesday, 25 March 2026
This series of images from NASA’s Hubble Space Telescope of the fragmenting comet C/2025 K1 (ATLAS) was taken over the course of three consecutive days: Nov. 8, 9, and 10, 2025. This is the first time Hubble has witnessed a comet so early in the process of breaking up.
Hubble caught K1 fragmenting into at least four pieces, each with a distinct coma, the fuzzy envelope of gas and dust that surrounds a comet’s icy nucleus. Hubble cleanly resolved the fragments, but from the ground, they appeared only as barely distinguishable blobs at that time. Hubble chronicled the sequence of events and showed exactly how the breakup happened.
Credit: NASA/Scott Eckley.
Thursday, 26 March 2026
These X-ray computed tomography (XCT) scans, released on March 17, 2026, give us a glimpse inside asteroid Bennu. They show the most common types of crack networks observed in Bennu samples. One has an extensive, interconnected framework of curved cracks, whereas the other has sparse, straight, flat fractures.
Credit: NASA/JPL-Caltech.
Friday, 27 March 2026
Seattle, Washington, is one of the cloudiest cities in the United States. But that infamous cloud cover is no match for the U.S.-Indian Earth satellite NISAR (NASA-ISRO Synthetic Aperture Radar), which is designed to peer straight through clouds. Doing so allows scientists to study the Pacific Northwest’s natural landmarks and bustling port cities like never before. This image, captured by the L-band SAR instrument on the NISAR mission on Nov. 10, 2025, shows Seattle at the center, with Bainbridge Island to the left.
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