Starship Asterisk*

starsurfer wrote: ↑Sun Sep 05, 2021 5:36 pm NGC 4860
https://esahubble.org/images/potw1838a/
Copyright: ESA/Hubble & NASA

Click to view full size image

ESA/Hubble wrote:

Colors & Filters

Optical
350 nm very broad

Optical
350 nm very broad

Optical
600 nm very broad

Optical
600 nm very broad

Image Credit: Yuri Beletsky (LCO)/ESO

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Like Atlas holding up the sky in the Ancient Greek myth, it looks like ESO’s Very Large Telescope (VLT) is supporting the Moon in this extraordinary picture of a total lunar eclipse at the Paranal Observatory in Chile’s Atacama Desert. The photograph was taken on 26 May 2021 by astrophotographer Yuri Beletsky and it is featured in the ESO Calendar 2022.

To take this Picture of the Week, some detailed planning was required on the part of the photographer. Careful calculations allowed him to pinpoint a location nine kilometres to the east of Paranal, where the setting lunar eclipse would be briefly visible just above the domes of the telescopes, glowing faintly in the early morning twilight.

A total lunar eclipse occurs when the Sun, Earth and Moon align, with the Earth between the Sun and Moon. The Earth’s shadow blocks direct sunlight, so that the only light reflected from the Moon’s surface has been refracted by Earth’s atmosphere, giving the Moon a reddish colour. Since sunlight is filtered by Earth’s atmosphere, astronomers often use lunar eclipses to understand the signatures that life can imprint on the atmosphere, which is extremely useful in our quest for life on other planets. ...

Image Credit: ESA/Hubble and NASA, A. Sarajedini

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This star-studded image from the NASA/ESA Hubble Space Telescope depicts NGC 6717, which lies more than 20,000 light-years from Earth in the constellation Sagittarius. NGC 6717 is a globular cluster, a roughly spherical collection of stars tightly bound together by gravity. Globular clusters contain more stars in their centres than their outer fringes, as this image aptly demonstrates; the sparsely populated edges of NGC 6717 are in stark contrast to the sparkling collection of stars at its centre.

The centre of the image also contains some interlopers from closer to home. Bright foreground stars close to Earth are surrounded by criss-cross diffraction spikes formed by starlight interacting with the structures supporting Hubble’s secondary mirror.

The area of the night sky which contains the constellation Sagittarius also contains the centre of the Milky Way, which is filled with light-absorbing gas and dust. This absorption of light — which astronomers refer to as extinction — makes studying globular clusters near the Galactic centre a challenging endeavour. To determine the properties of NGC 6717, astronomers relied on a combination of Hubble’s Wide Field Camera 3 (WFC3) and the Advanced Camera for Surveys (ACS).

Credit: P. Horálek & J. C. Casado / ESO

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Looking at this photo might make you feel a little topsy-turvy! This Picture of the Week captures both the Northern and Southern Hemisphere at once — the whole night’s sky in one mind-bending image — something that would be impossible to see in real life.

To create this image, photographers Petr Horálek and Juan Carlos Casado took two pictures at observatories located at the same latitudes in the Northern and Southern Hemispheres. The top half is a photo taken at the Instituto de Astrofísica de Canarias’ Roque de los Muchachos Observatory in La Palma in the Canary Islands, 29 degrees north of the equator, whilst the bottom half was taken at ESO’s La Silla Observatory in Chile’s Atacama Desert, 29 degrees south of the equator. When digitally stitched together, they create a continuous sweeping view of the night’s sky.

One of the most noticeable features in this picture is the eerie white glow radiating out vertically from its centre. This is the zodiacal light, a phenomenon caused by dust that pervades our Solar System scattering sunlight, which is only visible in areas with extremely dark skies free from light pollution. Shining brightly in the beam of the Northern Hemisphere Zodiacal Light is the planet Venus.

The bottom image shows several of the telescopes at La Silla, including the ESO 1-metre Schmidt telescope in the foreground. The reflective mirror seen upside-down in the top image is part of the Cherenkov Telescope Array (CTA), a group of gamma-ray telescopes observing some of the most energetic phenomena in the universe. A second array will be installed in the southern hemisphere close to ESO’s Paranal Observatory, via an agreement between CTA Observatory and ESO.

Click to view full size image 1 or image 2

Credit: ESA/Hubble and NASA, A. Nota, C. Britt

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This Picture of the Week showcases new views of the dual nature of the star AG Carinae, which was the target of the NASA/ESA Hubble Space Telescope’s 31st anniversary image in April 2020. This new perspective was developed thanks to Hubble’s observations of the star in 2020 and 2014, along with others captured by the telescope’s WFPC2 instrument in 1994. ...

The first image showcases the details of the ionised hydrogen and ionised nitrogen emissions from the nebula (seen here in red). In the second image, the blue demonstrates the contrasting appearance of the distribution of the dust that shines of reflected stellar light. Astronomers believe that the dust bubbles and filaments formed within and were shaped by powerful stellar wind.

This giant star is waging a tug-of-war between gravity and radiation to avoid self-destruction. The star is surrounded by an expanding shell of gas and dust — a nebula — that is shaped by the powerful winds emanating from the star. The nebula is about five light-years wide, equal to the distance from here to our nearest star, Alpha Centauri.

AG Carinae is formally classified as a Luminous Blue Variable because it is hot (blue), very luminous, and variable. Such stars are quite rare because there are not many stars that are so massive. Luminous Blue Variable stars continuously lose mass in the final stages of their life, during which a significant amount of stellar material is ejected into the surrounding interstellar space, until enough mass has been lost that the star has reached a stable state. ...