the-star-stuff:

Dec. 30, 1924: Hubble Reveals We Are Not Alone

1924: Astronomer Edwin Hubble announces that the spiral nebula Andromeda is actually a galaxy and that the Milky Way is just one of many galaxies in the universe.

Photo: Edwin Hubble’s 1920s observations of Andromeda (whose ultraviolet spectrum is rendered here) expanded our notions of the size and nature of a universe that is itself expanding.
Galaxy Evolution Explorer image courtesy NASA.

the-star-stuff:

Gravitational lensing twists distant galaxy into an Einstein Ring

Believe it or not, that blue horseshoe-shaped structure around that bright star is an entire galaxy, although it doesn’t really look anything like that. Its incredible twisted shape is a mirage created by a strange phenomenon called gravitational lensing.

Light isn’t immune to the force of gravity, and if it comes into contact with a large enough object - such as the combined mass of a large galaxy - it can become radically distorted. That’s what has happened here. The light coming from the galaxy in this image had to pass through another, much closer galaxy on its way to Earth. That light was twisted out of its original position, and the end result is that we see something radically different from the original image.

This is known as gravitational lensing, but the effect on display here is particularly unusual. Most of the time, lensing will simply redirect the light from the original source so that we see a pair of mirror images. But if the alignment of the gravitational lens is absolutely perfect, it will twist the light into a horseshoe shape like the one we see here.

This was all predicted in considerable detail seventy years ago by Albert Einstein - making this roughly the 30th most impressive thing he ever did that is still completely beyond most people’s comprehension. Today, structures like this are called Einstein Rings in his honor. They also serve an important function in modern astrophysics, as the extent of lensing can help us determine the total mass - and thus the amount of dark matter - in the foreground galaxy that created the lens effect in the first place.

Via NASA.

the-star-stuff:

The Center of our Galaxy

The center of the Milky Way above the hills of Azul, Argentina. You should be able to recognize scorpius, sagitarius and several nebulas and clusters. The “tire” tracks from Antares to the Milky Way are clearly visible.

Photo Credit: Luis Argerich 

subrosaecadrillie:

Carl Sagan tv show cosmos

space-is-great:

Sky Around Galaxy Cluster CL0024+1654 (ground-based image)

This is a 2.5-degree field around galaxy cluster CL0024+1654. The cluster galaxies are visible in the centre of the image in yellow. The image is a colour composite constructed from three Digitized Sky Survey images: Blue (shown in blue), Red (shown in green), and Infrared (shown in red.

(via spacetelescope.org)

moderation:

New Study Says Large Regions of Mars Could Sustain Life

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The question of whether present-day Mars could be habitable, and to what extent, has been the focus of long-running and intense debates. The surface, comparable to the dry valleys of Antarctica and the Atacama desert on Earth, is harsh, with well-below freezing temperatures most of the time (at an average of minus 63 degrees Celsius or minus 81 Fahrenheit), extreme dryness and a very thin atmosphere offering little protection from the Sun’s ultraviolet radiation. Most scientists would agree that the best place that any organisms could hope to survive and flourish would be underground. Now, a new study says that scenario is not only correct, but that large regions of Mars’ subsurface could be even more sustainable for life than previously thought.

Scientists from the Australian National University modeled conditions on Mars on a global scale and found that large regions could be capable of sustaining life – three percent of the planet actually, albeit mostly underground. By comparison, just one percent of Earth’s volume, from the central core to the upper atmosphere, is inhabited by some kind of life. They compared pressure and temperature conditions on Earth to those of Mars to come up with the surprising results.

The paper is currently available for free here.

(via  universetoday)

fragmented-blue:

Hubble Snaps Heavyweight of the Leo Triplet by NASA Goddard Photo and Video on Flickr.