Globular Cluster Messier 79

It’s beginning to look a lot like Christmas in this NASA/ESA Hubble Space Telescope image of a blizzard of stars, which resembles a swirling storm in a snow globe.

These stars make up the globular cluster Messier 79, located about 40 000 light-years from Earth in the constellation of Lepus (The Hare). Globular clusters are gravitationally bound groupings of up to one million stars. These giant “star globes” contain some of the oldest stars in our galaxy. Messier 79 is no exception; it contains about 150 000 stars, packed into an area measuring just roughly 120 light-years across.

This 11.7-billion-year-old star cluster was first discovered by French astronomer Pierre Méchain in 1780. Méchain reported the finding to his colleague Charles Messier, who included it in his catalogue of non-cometary objects: The Messier catalogue. About four years later, using a larger telescope than Messier’s, William Herschel was able to resolve the stars in Messier 79 and described it as a “globular star cluster.”

In this sparkling Hubble image, Sun-like stars appear yellow-white and the reddish stars are bright giants that are in the final stages of their lives. Most of the blue stars sprinkled throughout the cluster are aging “helium-burning” stars, which have exhausted their hydrogen fuel and are now fusing helium in their cores.

Image Credit: NASA and ESA, S. Djorgovski (Caltech) and F. Ferraro (University of Bologna)
Explanation from: https://www.spacetelescope.org/images/potw1751a/

Spiral Galaxy NGC 1398

This picture shows spectacular ribbons of gas and dust wrapping around the pearly centre of the barred spiral galaxy NGC 1398. This galaxy is located in the constellation of Fornax (The Furnace), approximately 65 million light-years away.

Rather than beginning at the very middle of the galaxy and swirling outwards, NGC 1398’s graceful spiral arms stem from a straight bar, formed of stars, that cuts through the galaxy’s central region. Most spiral galaxies — around two thirds — are observed to have this feature, but it’s not yet clear whether or how these bars affect a galaxy’s behaviour and development.

This image comprises data gathered by the FOcal Reducer/low dispersion Spectrograph 2 (FORS2) instrument, mounted on ESO’s Very Large Telescope (VLT) at Paranal Observatory, Chile. It shows NGC 1398 in striking detail, from the dark lanes of dust mottling its spiral arms, through to the pink-hued star-forming regions sprinkled throughout its outer regions.

This image was created as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/potw1801a/

The Bluest of Ice

Acquired on November 29 by Operation IceBridge during a flight to Victoria Land, this image shows an iceberg floating in Antarctica's McMurdo Sound. The part of the iceberg below water appears bluest primarily due to blue light from the water in the Sound. The undersides of some icebergs can be eroded away, exposing older, denser, and incredibly blue ice. Erosion can change an iceberg’s shape and cause it to flip, bringing the sculpted blue ice above the water’s surface. The unique step-like shape of this berg—compared to the tabular and more stable berg in the top-right of the image—suggests that it likely rotated sometime after calving.

Operation IceBridge—an airborne mission to map polar ice—recently made several flights out of the McMurdo and Amundsen-Scott South Pole stations, giving researchers greater access to the interior of the icy continent. For the ninth year in a row, flights over Antarctica have turned up ample science data, as well as spectacular images.

Image Credit: NASA/Chris Larsen
Explanation from: https://www.nasa.gov/image-feature/the-bluest-of-ice