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Stephan Mahlke on Unsplash

NASA Astronomy Picture of the Day:

Sunlit arms of a crescent moon seem to embrace the faint lunar night side in this dramatic celestial view from planet Earth. The single telephoto exposure tracking the sky was captured on the night of April 19, when a two day old Moon was near perigee in its elliptical orbit. On that date, the young Moon was also close on the sky to the lovely Pleiades Star Cluster. With the moonlight dimmed by clouds the Pleiades sister stars gather below the Moon's bright crescent, seen through a faint but colorful lunar corona. The lunar night side is illuminated by earthshine, sunlight reflected from the Earth itself. The Moon's ashen glow, also known as the "old moon in the young moon's arms," tends to be bright in the northern hemisphere spring. And for now, the Moon's orbit takes it near the Pleiades stars each month in planet Earth's sky, though their close conjunctions are easiest to see when the Moon is near a crescent phase.

Photo by Giorgia Hofer

Rapanui Rock during sunset, Sumner, Christchurch, New Zealand.

Michal Klajban, CC BY-SA 4.0, via Wikimedia Commons. View source.

Sonika Agarwal on Unsplash

NASA Astronomy Picture of the Day:

This is a map of the universe. The Dark Energy Spectroscopic Instrument (DESI) at Kitt Peak National Observatory, Arizona, has finished its five-year survey. It observed more than 47 million galaxies and quasars and created a 3D map centered on the Earth. Today's featured image shows a thin slice of these data: the black gaps indicate where our Galaxy obscures distant objects. The feathery web in the inset shows the large scale structure of the universe. Light of the most distant galaxies shown here travelled for 11 billion years to reach the Earth. Galaxies cluster throughout cosmic history under the competing influences of gravity and dark energy, responsible for the accelerated expansion of the universe. Analysis of early DESI results hinted at the possibility that dark energy, described as a cosmological constant by Albert Einstein, may not be constant after all. But we still have to wait for the analysis of the now complete dataset. The nature of dark energy is the biggest mystery of cosmology.

Saint George; upper altarpiece of the main altar of the parish church St. Georg, built in 1750 - 1751 by Peter Thumb (1681–1767), Hüfingen-Mundelfingen, Baden-Württemberg, Germany. Today is Saint George's Day.

H. Zell, CC BY-SA 3.0, via Wikimedia Commons. View source.