Starship Asterisk*

Credit: Gemini Observatory/NOIRLab/NSF/AURA/J. Chu

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Gemini North, one half of the international Gemini Observatory, a Program of NSF’s NOIRLab, uses a laser beam traveling through Earth’s atmosphere to adjust its adaptive optics. Like many large research telescopes today, Gemini North uses adaptive optics — bending its mirrors to compensate for atmospheric turbulence or “seeing”, which can blur the images of distant objects like stars and galaxies. The laser beam, seen here as a pink-orange stripe on the sky, travels into the upper atmosphere where it creates a bright spot of light that provides a reference point for the telescope to follow, and correct for, the atmospheric turbulence. This long-exposure photograph shows the laser tracking its target near the zenith, appearing to paint the sky with light. The stars appear as trails as they revolve around the north celestial pole during the long exposure.

Image Credit: ESA/Hubble & NASA, R. van der Burg et al

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The ultra-diffuse galaxy GAMA 526784 appears as a tenuous patch of light in this image from the NASA/ESA Hubble Space Telescope. This wispy object resides in the constellation Hydra, roughly four billion light-years from Earth. Ultra-diffuse galaxies such as GAMA 526784 have a number of peculiarities. For example, their dark matter content can be either extremely low or extremely high — ultra-diffuse galaxies have been observed with an almost complete lack of dark matter, whereas others consist of almost nothing but dark matter. Another oddity of this class of galaxies is their anomalous abundance of bright globular clusters, something not observed in other types of galaxies.

Hubble captured GAMA 526784 with the Advanced Camera for Surveys (ACS), which was installed in 2002 by astronauts during Hubble Servicing Mission 3B. Since then, the instrument has played a pivotal role in some of Hubble’s most impressive scientific results, including capturing the Hubble Ultra Deep Field. The ACS has also photographed Pluto in advance of the New Horizon mission, observed gargantuan gravitational lenses and found fully formed galaxies in the early Universe.

This image comes from a set of Hubble observations designed to shed light on the properties of ultra-diffuse galaxies. Hubble’s keen vision allowed astronomers to study GAMA 526784 in high resolution at ultraviolet wavelengths, helping to gauge the sizes and ages of the compact star-forming regions studding the galaxy.

Image Credit: ESO/Petr Horálek

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This image, taken at ESO’s La Silla Observatory in Chile’s Atacama Desert, shows the Milky Way as it peeks above the horizon, with two of the observatory’s telescopes bracketing the starry, dusty band as it stretches across the sky.

To the right stands the domed enclosure of the ESO 3.6-metre telescope and its adjacent smaller sibling, the now-decommissioned Coudé Auxiliary Telescope. To the left is the receiver dish for the Swedish–ESO Submillimetre Telescope, also now decommissioned.

Stretching into the distance to the left, and nearly at the centre of the image, lie the other buildings and telescope enclosures hosted at La Silla, their outlines silhouetted against the glowing sky. Visible in the far distance are city lights which, although faint in absolute terms, can become noticeable over long exposures such as this one. The soft glow of light just to the left of centre, which gently curves through the sky, is called zodiacal light, and it’s sunlight scattered by dust particles in the plane of the Solar System.

Hickson Compact Group 40 ~ Credit: NASA, ESA, & STScI

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The NASA/ESA Hubble Space Telescope is celebrating its 32nd birthday with a stunning look at an unusual close-knit collection of five galaxies, called the Hickson Compact Group 40. This snapshot reflects a special moment in their lifetimes as they fall together before they merge.

This menagerie includes three spiral-shaped galaxies, an elliptical galaxy and a lenticular (lens-like) galaxy. Somehow, these different galaxies have crossed paths to create an exceptionally crowded and eclectic galaxy sampler.

Caught in a leisurely gravitational dance, the whole group is so crowded that it could fit within a region of space that is less than twice the diameter of our Milky Way’s stellar disc.

Though such galaxy groupings can be found in the heart of huge galaxy clusters, these galaxies are notably isolated in their own small patch of the Universe, in the direction of the constellation Hydra. ...

Image Credit: ESA/Hubble & NASA, W. Keel

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Two merging galaxies in the VV689 system — nicknamed the Angel Wing — feature in this image from the NASA/ESA Hubble Space Telescope. Unlike chance alignments of galaxies which only appear to overlap as seen from our vantage point on Earth, the two galaxies in VV689 are in the midst of a collision. The galactic interaction has left the VV689 system almost completely symmetrical, giving the impression of a vast set of galactic wings.

This angelic image comes from a set of Hubble observations inspecting the highlights of the Galaxy Zoo citizen science project. This crowdsourced astronomy project relied on hundreds of thousands of volunteers to classify galaxies and help astronomers wade through a deluge of data from robotic telescopes. In the process, volunteers discovered a rogues’ gallery of weird and wonderful galaxy types, some of which had not previously been studied. A similar, ongoing project called Radio Galaxy Zoo is using the same crowdsourcing approach to locate supermassive black holes in distant galaxies.

Noteworthy objects from both projects were chosen for detailed follow-up observations with Hubble’s Advanced Camera for Surveys. In keeping with the crowdsourced nature of the Galaxy Zoo project, the targets for follow-up observations with Hubble were chosen via roughly 18 000 votes cast by the public. The selected targets include ring-shaped galaxies, unusual spirals, and a striking selection of galaxy mergers such as VV689.

Image Credit: ESO / Mahdi Zamani

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Floating in the sky above two of ESO’s Very Large Telescope (VLT) Auxiliary Telescopes are a pair of ethereal shapes. These are the Large and Small Magellanic Clouds — two of the 50 or so satellite galaxies that orbit our more massive Milky Way.

Despite being small compared to the Milky Way, the Magellanic Clouds still contain billions of stars. The Large Magellanic Cloud, in the bottom-right of the image, has a diameter of 14 000 light-years, and the Small Magellanic Cloud in the top-centre is 7000 light-years across. At distances of about 160 000 light-years and 200 000 light-years respectively these satellite galaxies are much closer to the Milky Way than our nearest major galaxy, Andromeda, 2.5 million light-years away, making them some of our closest neighbours.

The faint red emission in the sky is called airglow, and it's light naturally emitted by atoms and molecules high up in the atmosphere, oxygen in this case.

These ghostly galaxies can only be seen in the southern hemisphere, in skies that are unpolluted by light from cities. This is one of the reasons that ESO operates the VLT in the remote Chilean Atacama Desert — so that we can study such beguiling objects as the Magellanic Clouds.