November 22, 2016

Galaxy Cluster Abell 665

Galaxy Cluster Abell 665

Merging galaxy clusters can generate enormous shock waves, similar to cold fronts in weather on Earth. This system, known as Abell 665, has an extremely powerful shockwave, second only to the famous Bullet Cluster. Here, X-rays from Chandra (blue) show hot gas in the cluster. The bow wave shape of the shock is shown by the large white region near the center of the image. The Chandra image has been added to radio emission (purple) and visible light data from the Sloan Digital Sky Survey showing galaxies and stars (white).

Image Credit: X-ray: NASA/CXC/Univ. of Alabama/S.Dasadia et al, Radio: NSF/NRAO/VLA, Optical: SDSS
Explanation from: https://www.nasa.gov/mission_pages/chandra/abell-665.html

Storm clouds over Yorkshire

Storm clouds over Yorkshire

Yorkshire, England, UK

Image Credit & Copyright: Mat Robinson

Clouds over Atlantic Ocean seen from the International Space Station

Clouds over Atlantic Ocean seen from the International Space Station

ISS, Orbit of the Earth
September 2016

Image Credit: NASA/ESA

November 21, 2016

Spiral Galaxy NGC 986

Spiral Galaxy NGC 986

This picture shows the spiral galaxy NGC 986 in the constellation of Fornax (The Furnace). The galaxy, which was discovered in 1826 by the Scottish astronomer James Dunlop, is not often imaged due to its proximity to the famous and rich Fornax Cluster of galaxies. Which is a shame, as this galaxy is not only a great scientific object, but also very pretty.

The galaxy is about 56 million light-years away and seen almost perfectly from the top, or — as astronomers say — face-on. This allows us to see the two main spiral arms and also a central bar-shaped structure, composed of stars and dust, which makes it a barred spiral galaxy.

Astronomical surveys have shown that about two thirds of all spiral galaxies contain a bar, including the Milky Way. This makes NGC 986 the perfect place to study the structure of galaxies and find out more about our own home galaxy, which is difficult to study from within.

This view from the FORS instrument on ESO’s Very Large Telescope at the Paranal Observatory in northern Chile comes from 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/potw1605a/

Milky Way Galaxy seen over Dinosaur National Monument

Milky Way

Colorado/Utah, USA
October 14, 2015

Image Credit & Copyright: Dan Duriscoe

Aurora over Indian Ocean seen from the International Space Station

Aurora over Indian Ocean seen from the International Space Station

ISS, Orbit of the Earth
August 2016

Image Credit: NASA/ESA

November 20, 2016

Elliptical Galaxy NGC 3923

Elliptical Galaxy NGC 3923

The glowing object in this image is an elliptical galaxy called NGC 3923. It is located over 90 million light-years away in the constellation of Hydra.

NGC 3923 is an example of a shell galaxy where the stars in its halo are arranged in layers.

Finding concentric shells of stars enclosing a galaxy is quite common and is observed in many elliptical galaxies. In fact, every tenth elliptical galaxy exhibits this onion-like structure, which has never been observed in spiral galaxies. The shell-like structures are thought to develop as a consequence of galactic cannibalism, when a larger galaxy ingests a smaller companion. As the two centres approach, they initially oscillate about a common centre, and this oscillation ripples outwards forming the shells of stars just as ripples on a pond spread when the surface is disturbed.

NGC 3923 has over twenty shells, with only a few of the outer ones visible in this image and its shells are much more subtle than those of other shell galaxies. The shells of this galaxy are also interestingly symmetrical, while other shell galaxies are more skewed.

Image Credit: ESA/Hubble & NASA, Judy Schmidt
Explanation from: https://www.spacetelescope.org/images/potw1519a/

Galaxy Cluster RX J0603.3+4214

Galaxy Cluster RX J0603.3+4214

The phenomenon of pareidolia is when people see familiar shapes in images. This galaxy cluster has invoked the nickname of the “Toothbrush Cluster” because of its resemblance to the dental tool. In fact, the stem of the brush is due to radio waves (green) while the diffuse emission where the toothpaste would go is produced by X-rays observed by Chandra (purple). Visible light data from the Subaru telescope show galaxies and stars (white) and a map from gravitational lensing (blue) shows the concentration of the mass, which is mostly (about 80%) dark matter.

Image Credit: X-ray: NASA/CXC/SAO/R. van Weeren et al; Radio: LOFAR/ASTRON; Optical: NAOJ/Subaru
Explanation from: https://www.nasa.gov/mission_pages/chandra/toothbrush-cluster-rx-j060334214.html

Sunrise, Earth and Solar Arrays of the International Space Station

Sunrise, Earth and Solar Arrays of the International Space Station

ISS, Orbit of the Earth
September 2016

Image Credit: NASA/ESA