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NASA Astronomy Picture of the Day:

Like salsa verde on your favorite burrito, a green aurora slathers up the sky in this 2017 June 25 snapshot from the International Space Station. About 400 kilometers (250 miles) above Earth, the orbiting station is itself within the upper realm of the auroral displays. Aurorae have the signature colors of excited molecules and atoms at the low densities found at extreme altitudes. Emission from atomic oxygen dominates this view. The tantalizing glow is green at lower altitudes, but rarer reddish bands extend above the space station's horizon. The orbital scene was captured while passing over a point south and east of Australia, with stars above the horizon at the right belonging to the constellation Canis Major, Orion's big dog. Sirius, alpha star of Canis Major, is the brightest star near the Earth's limb.

Partially frozen Gurudongmar Lake, a glacial lake located to the north of the Himalayas in the northeast Indian state of Sikkim at an altitude of over 5,150 metres (16,900 ft). The lake is fed by glaciers of the Khangchengyao massif, forms the headwaters of the Teesta river and is considered sacred by Buddhists and Sikhs. Today is Sikkim Day, which commemorates the formation of Sikkim as a state of India in 1975, following a popular referendum and full merger after decades of being a protectorate since 1947.

Original: Yoghya Derivative work: UnpetitproleX, CC BY-SA 4.0, via Wikimedia Commons. View source.

Vivek Doshi on Unsplash

NASA Astronomy Picture of the Day:

Comet R3 PanSTARRS might be best remembered as an Orion comet. A key reason is because Comet C/2025 R3 (PanSTARRS) was near its most spectacular -- in terms of tail visibility -- when passing in front of the iconic constellation. Although rare, other bright comets, too, have ventured across Orion, including Lovejoy in 2015, Hale-Bopp in 1997, and the Great Comet of 1264. Best visible in long duration exposures, the featured image was captured last week from the Craigieburn Mountain Range in New Zealand. Visible in the deep background image are the Orion Nebula, Barnard's Loop, and through R3's tail, the bright star Saiph, the sixth brightest star in the constellation of Orion. Comet R3 PanSTARRS continues to fade as it moves further south, passing into the constellation of the Unicorn (Monoceros) in the next few days. Sky Surprise: What picture did APOD feature on your birthday? (after 1995)

Photo by Chester Hall-Fernandez

Australian brushturkey (Alectura lathami) female, Crater Lakes, Atherton Tableland, Queensland, Australia.

Charles J. Sharp, CC BY-SA 4.0, via Wikimedia Commons. View source.

Friedrich Wilhelm Nietzsche (1844 -1900) German philosopher, cultural critic, composer, poet, philologist, and a Latin and Greek scholar. 

Jose Llamas on Unsplash

NASA Astronomy Picture of the Day:

What are some of the most interesting astronomical objects you can see in the night sky? Armed with a good pair of binoculars or a small telescope, if you live in the Northern Hemisphere, you can look for the very popular objects in the Messier Catalog. Most of them, but not all, are also visible from the southern half of the Earth. The featured image shows all 110 objects in the catalog at uniform scale -- the same magnification. Charles Messier created the catalog in the 18th century. He was interested in comets, and his catalog was a list of known comet-like "objects to avoid" in the sky when observing or hunting for comets. The deep sky objects in the catalog include a supernova remnant (the Crab Nebula, M1), other galaxies (such as Andromeda, M31), nebulae (e.g. the Orion Nebula, M42, a star-forming region) and stellar clusters (such as the Pleiades, M45, a bright young open cluster).