Star Clusters in 30 Doradus Nebula

This is a Hubble Space Telescope image of a pair of star clusters that are believed to be in the early stages of merging. The clusters lie in the gigantic 30 Doradus Nebula, which is 170,000 light-years from Earth.

Hubble's circumstantial evidence for the impending collision comes from seeing an elongated structure in the cluster at upper left, and from measuring a different age between the two clusters. Also, the unusually large number of high-velocity stars around 30 Doradus can finally be explained if a small cluster has merged into the big cluster R136 in the centre of the Tarantula Nebula.

This nearby example of cluster interaction yields insights into how star clusters may have formed in the early Universe.

The Hubble observations, made with the Wide Field Camera 3, were taken 20-27 October, 2009. The blue colour is light from the hottest, most massive stars; the green from the glow of oxygen; and the red from fluorescing hydrogen.

Image Credit: NASA, ESA
Explanation from: https://www.spacetelescope.org/images/opo1235b/

Pingualuit Crater

The Pingualuit Crater, formerly called Chubb Crater and later New Quebec Crater, is a young impact crater, by geological standards, located on the Ungava Peninsula, in the administrative region of Nord-du-Québec, in Quebec, in Canada. It is 3.44 km (2.14 mi) in diameter, and is estimated to be 1.4 ± 0.1 million years old (Pleistocene).

The crater is exposed to the surface, rising 160 m (520 ft) above the surrounding tundra and is 400 m (1,300 ft) deep. The 267 m (876 ft) deep annular Pingualuk Lake fills the hollow, and is one of the deepest lakes in North America. The lake also holds some of the purest fresh water in the world, with a salinity level of less than 3 ppm (the salinity level of the Great Lakes is 500 ppm). The lake has no inlets or apparent outlets, so the water accumulates solely from rain and snow and is only lost through evaporation. It is one of the most transparent lakes in the world, with Secchi disk visible more than 35 m (115 ft) deep.

The crater was formed by a meteorite impact 1.4 Ma, as estimated by 40Ar/39Ar dating of impact melt rocks. An analysis of these rocks also revealed planar deformation features as well as the composition of the meteorite itself. The Ir, Ni, Co and Cr enrichments found in impact melt samples suggest that the meteorite was chondritic in nature.

Image Credit: NASA/Jeff Schmaltz
Explanation from: https://en.wikipedia.org/wiki/Pingualuit_crater

Cloud shadows on Pacific Ocean seen from International Space Station

ISS, Orbit of the Earth

August 2016

Image Credit: NASA/ESA