Stellar Streams in the Local Universe

The twenty galaxies arrayed in these panels are part of an ambitious astronomical survey of tidal stellar streams. Each panel presents a composite view; a deep, inverted image taken from publicly available imaging surveys of a field that surrounds a nearby massive galaxy image. The inverted images reveal faint cosmic structures, star streams hundreds of thousands of light-years across, that result from the gravitational disruption and eventual merger of satellite galaxies in the local universe. Such surveys of mergers and gravitational tidal interactions between massive galaxies and their dwarf satellites are crucial guides for current models of galaxy formation and cosmology. Of course, the detection of stellar streams in the neighboring Andromeda Galaxy and our own Milky Way also offers spectacular evidence for ongoing satellite galaxy disruption within our more local galaxy group.

from NASA https://ift.tt/bevwimQ

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Lightning and Orion Beyond Uluru

What's happening behind Uluru? A United Nations World Heritage Site , Uluru is an extraordinary 350-meter high mountain in central Australia that rises sharply from nearly flat surroundings. Composed of sandstone , Uluru has slowly formed over the past 300 million years as softer rock eroded away. In the background of the featured image taken in mid-May, a raging thunderstorm is visible. Far behind both Uluru and the thunderstorm is a star-filled sky highlighted by the constellation of Orion. The Uluru region has been a home to humans for over 22,000 years. Local indigenous people have long noted that when the stars that compose the modern constellation of Orion first appear in the night sky, a hot season involving lightning storm s will soon be arriving. from NASA https://ift.tt/3uy2PLM

A Phoenix Aurora over Iceland

All of the other aurora watchers had gone home. By 3:30 am in Iceland , on a quiet September night, much of that night's auroras had died down. Suddenly, unexpectedly, a new burst of particles streamed down from space, lighting up the Earth's atmosphere once again. This time, surprisingly, pareidolia cally, the night lit up with an amazing shape reminiscent of a giant phoenix . With camera equipment at the ready, two quick sky images were taken, followed immediately by a third of the land. The mountain in the background is Helgafell , while the small foreground river is called Kald��, both located about 30 kilometers north of Iceland's capital Reykjav��k . Seasoned skywatchers will note that just above the mountain, toward the left, is the constellation of Orion , while the Pleiades star cluster is also visible just above the frame center. The 2016 aurora , which lasted only a minute and was soon gone forever -- would possibly be dismissed as an fanciful fable -...

Stephans Quintet from Webb, Hubble, and Subaru

OK, but why can't you combine images from Webb and Hubble? You can, and today's featured image shows one impressive result. Although the recently launched James Webb Space Telescope (Webb) has a larger mirror than Hubble, it specializes in infrared light and can't see blue -- only up to about orange. Conversely, the Hubble Space Telescope (Hubble) has a smaller mirror than Webb and can't see as far into the infrared as Webb, but can image not only blue light but even ultraviolet . Therefore, Webb and Hubble data can be combined to create images across a wider variety of colors. The featured image of four galaxies from Stephan's Quintet shows Webb images as red and also includes images taken by Japan 's ground-based Subaru telescope in Hawaii . Because image data for Webb , Hubble , and Subaru are made freely available, anyone around the world can process it themselves, and even create intriguing and scientifically useful multi-observatory montages...

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