Image of the Day May 24, 2026
The Trifid Nebula shows three kinds of cloud in one frame
NASA’s April image article on the Trifid Nebula is a good Sunday choice because Messier 20 refuses to be just one object. It is an emission nebula where young stars light hydrogen gas, a reflection nebula where dust scatters blue starlight, and a dark nebula where colder lanes cut through the glow. That mixture makes it more than a pretty deep-sky picture: it is a compact lesson in star formation, with gas, dust, radiation and gravity all visible in the same field. The longer you look, the more the image turns from colour into physics.
Credit · NASA
On This Day 64 years ago
1962
Scott Carpenter flew Aurora 7
On May 24, 1962, NASA astronaut Scott Carpenter flew Aurora 7, the second American orbital flight of Project Mercury. Carpenter orbited Earth three times, following John Glenn’s pioneering orbital mission earlier that year, and helped prove that the United States could repeat human spaceflight rather than merely achieve it once. The mission was untidy: fuel use, manual control, timing errors and re-entry targeting left Carpenter splashing down far from the planned recovery area. That messiness is part of why Aurora 7 matters. Early spaceflight was still an experimental blend of human judgement, fragile automation and unforgiving orbital mechanics.
Paper of the Day arXiv · cs.LG
Observation of Gravitational Waves from a Binary Black Hole Merger
LIGO Scientific Collaboration and Virgo Collaboration
This is the gravitational-wave paper: the announcement that LIGO had observed GW150914, a signal from two merging black holes. The abstract describes a transient event detected by the two Advanced LIGO detectors on September 14, 2015, matching general relativity’s prediction for the inspiral and merger of black holes of roughly 36 and 29 solar masses. About three solar masses were radiated away as gravitational-wave energy. Its importance is hard to overstate: direct gravitational-wave detection opened a new observing channel for astronomy, not light from the universe but spacetime itself ringing.
arXiv:1602.03837 →