domingo, 28 de agosto de 2016

APOD - Abell 370: Galaxy Cluster Gravitational Lens

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2016 August 28
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Abell 370: Galaxy Cluster Gravitational Lens
Image Credit: NASA, ESA, and the Hubble SM4 ERO Team & ST-ECF

Explanation: What is that strange arc? While imaging the cluster of galaxies Abell 370, astronomers had noted an unusual arc to the right of many cluster galaxies. Although curious, one initial response was to avoid commenting on the arc because nothing like it had ever been noted before. In the mid-1980s, however, better images allowed astronomers to identify the arc as a prototype of a new kind of astrophysical phenomenon -- the gravitational lens effect of entire cluster of galaxies on background galaxies. Today, we know that this arc actually consists of two distorted images of a fairly normal galaxy that happened to lie far behind the huge cluster. Abell 370's gravity caused the background galaxies' light -- and others -- to spread out and come to the observer along multiple paths, not unlike a distant light appears through the stem of a wine glass. In mid-July of 2009, astronomers used the then just-upgraded Hubble Space Telescope to image Abell 370 and its gravitational lens images in unprecedented detail. Almost all of the yellow images featured here are galaxies in the Abell 370 cluster. An astute eye can pick up many strange arcs and distorted arclets, however, that are actually images of more distant galaxies. Studying Abell 370 and its images gives astronomers a unique window into the distribution of normal and dark matter in galaxy clusters and the universe.

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Tomorrow's picture: young suns


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sábado, 27 de agosto de 2016

APOD - Lunar Orbiter Earthset

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2016 August 27
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Lunar Orbiter Earthset
Image Credit: NASA / Lunar Orbiter Image Recovery Project

Explanation: August 10th was the 50th anniversary of the launch of Lunar Orbiter 1. It was the first of five Lunar Orbiters intended to photograph the Moon's surface to aid in the selection of future landing sites. That spacecraft's camera captured the data used in this restored, high-resolution version of its historic first image of Earth from the Moon on August 23, 1966 while on its 16th lunar orbit. Hanging almost stationary in the sky when viewed from the lunar surface, Earth appears to be setting beyond the rugged lunar horizon from the perspective of the orbiting spacecraft. Two years later, the Apollo 8 crew would record a more famous scene in color: Earthrise from lunar orbit.

Tomorrow's picture: galaxies everywhere


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viernes, 26 de agosto de 2016

APOD - The Milky Way Sets

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2016 August 26
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The Milky Way Sets
Image Credit & Copyright: Juan Carlos Casado (TWAN, Earth and Stars)

Explanation: Under dark skies the setting of the Milky Way can be a dramatic sight. Stretching nearly parallel to the horizon, this rich, edge-on vista of our galaxy above the dusty Namibian desert stretches from bright, southern Centaurus (left) to Cepheus in the north (right). From early August, the digitally stitched, panoramic night skyscape captures the Milky Way's congeries of stars and rivers of cosmic dust, along with colors of nebulae not readily seen with the eye. Mars, Saturn, and Antares, visible even in more luminous night skies, form the the bright celestial triangle just touching the trees below the galaxy's central bulge. Of course, our own galaxy is not the only galaxy in the scene. Two other major members of our local group, the Andromeda Galaxy and the Triangulum Galaxy, lie near the right edge of the frame, beyond the arc of the setting Milky Way.

Tomorrow's picture: when planet Earth sets


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jueves, 25 de agosto de 2016

APOD - Closest Star has Potentially Habitable Planet

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2016 August 25
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Closest Star has Potentially Habitable Planet
Image Credit & License: Y. Beletsky (LCO), ESO, Pale Red Dot Team

Explanation: The star closest to the Sun has a planet similar to the Earth. As announced yesterday, recent observations confirmed that this planet not only exists but inhabits a zone where its surface temperature could allow liquid water, a key ingredient for life on Earth. It is not yet known if this planet, Proxima b, has any life. Even if not, its potential ability to sustain liquid water might make it a good first hop for humanity's future trips out into the Milky Way Galaxy. Although the planet's parent star, Proxima Centauri, is cooler and redder than our Sun, one of the other two stars in the Alpha Centauri star system is very similar to our Sun. The featured image shows the sky location of Proxima Centauri in southern skies behind the telescope that made many of the discovery observations: ESO's 3.6-meter telescope in La Silla, Chile. The discovered planet orbits close in -- so close one year there takes only 11 days on Earth. The planet was discovered by the ESO's Pale Red Dot collaboration. Although seemingly unlikely, if Proxima b does have intelligent life, at 4.25 light years distance it is close enough to Earth for two-way communication.

Tomorrow's picture: when planet Earth sets


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miércoles, 24 de agosto de 2016

APOD - Curiosity at Murray Buttes on Mars

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2016 August 24
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Curiosity at Murray Buttes on Mars
Image Credit: NASA, JPL-Caltech, MSSS

Explanation: What are these unusual lumps on Mars? As NASA's robotic Curiosity rover continues rolling across Mars, it is now approaching Murray Buttes. Several of the 15-meter high buttes are visible ahead in this horizontally compressed 360-degree across image taken inside Gale Crater earlier this month. The buttes are thought similar to Earth buttes in that they are capped with dense rock that is relatively resistant to erosion. In the image center is Curiosity's "arm" and "hand" used to examine rocks up close, drill into rocks, and collect samples. Curiosity has reached its four year anniversary on Mars and has been cleared to spend the next two years further exploring the slopes of Mount Sharp, the peak of which is the distant light-colored structure visible on the far left.

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Tomorrow's picture: young suns


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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