Found Images: 2021 April

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Have you seen a great image or video somewhere that you think would make a great APOD? Nominate it for APOD! Please post as much information here as you have about the image/video with a link to any source(s) for it you know of here, and the editors will take a look.

When posting the image itself, please do not post anything larger than a thumbnail here; please honor the copyright holder's copyright.

Please keep hotlinked images under 500K.

Thank you!

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vdB4 and NGC 225
https://www.hansonastronomy.com/vdb-4
Copyright: Mark Hanson

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Sh2-188
https://www.astrobin.com/f9iw94/
Copyright: Chris Sullivan

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M77
https://www.eso.org/public/news/eso1720/
Copyright: ESO

Click to view full size image

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M88
http://www.karelteuwen.be/photo_page.ph ... 4&album=18
Copyright: Karel Teuwen

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M83
https://www.rolfolsenastrophotography.c ... /i-pzgwH8f
Copyright: Rolf Olsen

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A Watercolour Sky
ESO Picture of the Week | 2021 Apr 05

Image Credit: ESO/Petr Horálek

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The Atacama Desert in Chile is one of the darkest and most peaceful astronomical sites on Earth — and has, as a result, proven to be the perfect location for ESO’s ]various observatories and powerful instruments.

This view shows ESO’s Paranal Observatory, home to the behemoth Very Large Telescope (VLT). The constituent telescopes of the VLT can be seen standing sentinel beneath a star-studded sky featuring the glittering arch of our Galaxy, and the glowing Magellanic Clouds (left). As this image demonstrates, the sky over Paranal isn’t completely dark; after sunset, the beauty of the Universe is overshadowed by that of Earth’s own atmosphere, which glows in multiple hues and paints the sky like a watercolour. The playful brushstrokes of the faraway emission nebulae that adorn the Milky Way and the constellation of Orion (The Hunter) in the upper centre of the frame, are joined by the soft swaths of green, yellow, red, and orange lying close to the horizon.

This colourful palette is airglow — atmospheric radiance caused by chemical processes that occur up to about a few hundred kilometres above ground. Just after the Sun has set in the west (right), its strong light also reflects from specks of rock and ice sitting between it and us, causing them to glimmer and show up as a diffuse white ray (lower centre).

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Spiral Snapshot
ESA Hubble Picture of the Week | 2021 Apr 05

Image Credit: ESA/Hubble & NASA, ESO, J. Lee, and the PHANGS-HST Team

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The luminous heart of the galaxy M61 dominates this image, framed by its winding spiral arms threaded with dark tendrils of dust. As well as the usual bright bands of stars, the spiral arms of M61 are studded with ruby-red patches of light. Tell-tale signs of recent star formation, these glowing regions lead to M61’s classification as a starburst galaxy.

Though the gleaming spiral of this galaxy makes for a spectacular sight, one of the most interesting features of M61 lurks unseen at the centre of this image. As well as widespread pockets of star formation, M61 hosts a supermassive black hole more than 5 million times as massive as the Sun.

M61 appears almost face-on, making it a popular subject for astronomical images, even though the galaxy lies more than 52 million light-years from Earth. This particular astronomical image incorporates data from not only Hubble, but also the FORS camera at the European Southern Observatory’s Very Large Telescope, together revealing M61 in unprecedented detail. This striking image is one of many examples of telescope teamwork — astronomers frequently combine data from ground-based and space-based telescopes to learn more about the Universe.

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H3-75
https://www.imagingdeepspace.com/h-3-75.html
Copyright: Peter Goodhew

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Jones 1
https://pbase.com/skybox/image/171355784
Copyright: Kevin Quin

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NGC 246
http://www.cielaustral.com/galerie/photo130.htm
Copyright: Ciel Austral

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3C 58
http://outters.fr/wp/?p=9040
Copyright: Nicolas Outters

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NGC 2541
https://noirlab.edu/public/images/iotw2030a/
Copyright: KPNO/NOIRLab/NSF/AURA
Acknowledgement: PI: M T. Patterson (New Mexico State University)
Processing: Travis Rector (University of Alaska Anchorage), Mahdi Zamani & Davide de Martin

Click to view full size image

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MBM 25
http://afesan.es/Deepspace/slides/MBM%2 ... nx%29.html
Copyright: Antonio Sánchez

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Milky Way across the Desert
ESO Picture of the Week | 2021 Apr 12

Image Credit: ESO/Petr Horálek

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Great care is taken to ensure that the site for a new telescope will provide the best possible observing conditions.

This picture of the week was captured in 2019 by ESO photo ambassador Petr Horálek from the top of Cerro Armazones, Chile, where the Extremely Large Telescope (ELT) is being constructed. Situated in the heart of the Atacama desert, at an altitude of 3046 metres, this high and dry location will be vital to showcase and utilise the ELT’s incredible observational power.

This extraordinary panorama of the Atacama desert frames a sprawling view of our own Milky Way galaxy, seen with stunning clarity as a result of the minimum light pollution in this remote area. Massive interstellar dust clouds obscure the more distant starlight, leading to the distinctive “mottled” band in the night sky.

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Light Bends from the Beyond
ESA Hubble Picture of the Week | 2021 Apr 12

Image Credit: ESA/Hubble & NASA, D. Coe

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This extraordinary image from the NASA/ESA Hubble Space Telescope of the galaxy cluster Abell 2813 (also known as ACO 2813) has an almost delicate beauty, which also illustrates the remarkable physics at work within it. The image spectacularly demonstrates the concept of gravitational lensing.

In amongst the tiny dots, spirals and ovals that are the galaxies that belong to the cluster, there are several distinct crescent shapes. These curved arcs of light are strong examples of a phenomenon known as gravitational lensing. The image was compiled using observations taken with the Hubble Space Telescope’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3).

Gravitational lensing occurs when an object’s mass causes light to bend. The curved crescents and s-shapes of light in this image are not curved galaxies, but are light from galaxies that actually lie beyond Abell 2813. The galaxy cluster has so much mass that it acts as a gravitational lens, causing light from more distant galaxies to bend around it. These distortions can appear as many different shapes, such as long lines or arcs.

This very visual evidence that mass causes light to bend has been famously used as a proof of one of the most famous scientific theories: Einstein’s theory of general relativity.

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Patchick 5
https://www.astrobin.com/n7crrt/
Copyright: Boris Chausov

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Patchick 6
https://www.astrobin.com/7vef4o/C/
Copyright: Rauno Päivinen

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NGC 1808
https://www.astrobin.com/wmwk0e/
Copyright: Geoff Smith

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NGC 1097
https://www.astrobin.com/lzjkdd/
Copyright: Yves Jongen

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M94
https://www.astrobin.com/vdvuav/
Data: Barry Wilson and Steve Milne
Processing: Barry Wilson

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IC 2167
http://www.chart32.de/index.php/component/k2/item/406
Copyright: CHART32
Processing: Bernd Flach-Wilken

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Hen 2-72
http://members.pcug.org.au/~stevec/hen2 ... 0_RC14.htm
Copyright: Steve Crouch

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In a Cosmic Wonderland
ESO Picture of the Week | 2021 Apr 19

Image Credit: ESO/Petr Horálek

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This panoramic selfie was taken on 9 April 2016 by ESO Photo Ambassador Petr Horálek. Petr was in the Chilean Atacama Desert as a member of ESO’s Fulldome Expedition team, a select group of photographers who captured an array of stunning, ultra-high-definition visuals for use primarily in the ESO Supernova Planetarium & Visitor Centre.

The landscape looms large around photographer Petr in this image, making him appear small beneath the striking Chilean sky. He can be seen standing just beneath a column of zodiacal light — perfect positioning that makes this image appear even more otherworldly.

The wide, round-topped objects visible here are some of the 12-metre antennas comprising the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA is the largest ground-based astronomical observatory in the world, and is located on the Chajnantor Plateau in Chile at an altitude of 5000 metres. A total of 66 antennas make up the array, and can be connected together in different configurations to act as a single telescope, known as an interferometer. This arrangement enables ALMA to be the most powerful explorer of the Universe in millimetre and submillimetre light, the kind of light that is produced by cool, distant, ancient phenomena throughout the cosmos, allowing us to explore the birth of stars, the formation of exoplanets, and distant galaxies.

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Galactic Close-Up
ESA Hubble Picture of the Week | 2021 Apr 19

Image Credit: ESA/Hubble & NASA, J. Maund

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This image shows a close-up portrait of the magnificent spiral galaxy NGC 4603, which lies over 100 million light-years away in the constellation of Centaurus (The Centaur). Bright bands of blue young stars make up the arms of this galaxy, which wind lazily outwards from the luminous core. The intricate red-brown filaments threading through the spiral arms are known as dust lanes, and consist of dense clouds of dust which obscure the diffuse starlight from the galaxy.

This galaxy is a familiar subject for Hubble. In the last years of the twentieth century, NGC 4063 was keenly and closely watched for signs of a peculiar class of stars known as Cepheid variables. These stars have a luminosity closely tied to the period with which they darken and brighten, allowing astronomers to accurately measure how far they are from Earth. Distance measurements from Cepheid variables are key to measuring the furthest distances in the Universe, and were one of the factors used by Georges Lemaître and Edwin Hubble to show that the Universe is expanding.