Astronomy

This astounding view of galaxy cluster MACSJ0025 demonstrates how ordinary matter and mysterious dark matter interact. The blue cloud-shaped parts flanking the centre show the position of dark matter, mapped by the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope. The pink middle indicates ordinary matter, charted by NASA’s Chandra X-Ray Observatory. The position of the two matter types shown in the image are explained by MACSJ0025’s origin. It was formed when a pair of large galaxy clusters collided.

Ordinary matter in the form of hot gas slowed down and pooled at the centre but ghostly dark matter passed straight through. Hubble used a technique known as gravitational lensing to obtain its data. The light observed was bent by the gravitationally massive galaxy cluster, resulting in an incredibly detailed image. This technique was originally predicted by Einstein. MACSJ0025 is located in the constellation Cetus, the Whale.

The powerful collision of galaxy clusters provides striking evidence for dark matter and insight into its properties. This newly studied cluster shows a clear separation between dark and ordinary matter. This helps answer a crucial question about whether dark matter interacts with itself in ways other than via gravitational forces.

Credit: NASA, ESA, CXC, M. Bradac (University of California, Santa Barbara, USA), and S. Allen (Stanford University, USA).

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Commemorating the 100,000th orbit of the Hubble Space Telescope around the earth, scientists have aimed it to take a snapshot of a dazzling region of celestial birth and renewal. The Hubble’s camera peered into a small portion of the nebula near the star cluster NGC 2074. The region is a firestorm of raw stellar creation, perhaps triggered by a nearby supernova explosion. It lies about 170,000 light-years away near the Tarantula nebula, one of the most active star-forming regions in our local group of galaxies.

The three-dimensional-looking image reveals dramatic ridges and valleys of dust, serpent-head “pillars of creation,” and gaseous filaments glowing fiercely under torrential ultraviolet radiation. The approximately 100 light-year wide region is on the edge of a dark molecular cloud that is an incubator for the birth of new stars.

The region is in the Large Magellanic Cloud (LMC), a satellite of our Milky Way galaxy. It is a fascinating laboratory for observing star-formation regions and their evolution. Dwarf galaxies like the LMC are considered to be the primitive building blocks of larger galaxies. The high-energy radiation blazing out from clusters of hot young stars already born in NGC 2074 is sculpting the wall of the nebula by slowly eroding it away. Another young cluster may be hidden beneath a circle of brilliant blue gas at the bottom center of the image.

The representative color image of NGC 2074 above was taken on August 10, 2008, with Hubble’s Wide Field Planetary Camera 2. Red shows emission from sulphur atoms, green from glowing hydrogen, and blue from glowing oxygen. (Picture credits: NASA/ESA/M. Livio [STScI])

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We sometime seeing full moon on the horizon, and thinks that it seems larger than usual. It is actually an illusion. Because we are accustomed to seeing clouds only a few miles overhead but clouds touching the horizon are hundreds of miles away, our minds induce us to believe that things on the horizon are farther than those above us. Hence if we notice the moon lower in the sky, it looks like farther and bigger. However, it’s all in our minds.

The moon at the horizon is actually not bigger than it is when overhead. It’s the timing of the summer solstice and the full moon that affects the moon’s appearance as the sun and full moon are like children playing on a see-saw. When the sun is soaring in the sky, the moon stays lower which makes a long-lasting and bigger version of the illusion.

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A partial lunar eclipse will took place on August 16, 2008. It is visibile primarily from the Eastern Hemisphere as well as eastern South America. Greatest eclipse takes place at 21:10:06 UT when the eclipse magnitude will reach 0.8076. The timings of the major phases of the eclipse are listed below.

Penumbral Eclipse Begins:   18:24:49 UT
Partial Eclipse Begins:     19:36:07 UT
Greatest Eclipse:           21:10:09 UT
Partial Eclipse Ends:       22:44:16 UT
Penumbral Eclipse Ends:     23:55:25 UT

The Moon’s trajectory takes it through the northern umbral shadow, resulting in a partial eclipse that lasts 3 hours 8 minutes. At mid-eclipse the Moon’s northern limb passes 5.9 arc-minutes outside the umbra’s northern edge. The Moon’s southern edge is then 16.5 arc-minutes from the shadow’s centre.

This eclipse is also the last eclipse on 2008. (Source: NASA)

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While using the www.galaxyzoo.org website to classify images of galaxies, Hanny van Arkel, a Dutch school teacher, and volunteer in the Galaxy Zoo project, found this object on the archived images of the night sky. Soon after she posted about the image, it became known as “Hanny’s Voorwerp” (Dutch for “object”) on the Galaxy Zoo forum. Astronomers who run the site began to investigate and soon realized van Arkel might have found a new class of astronomical object.

Scientists working at telescopes around the world and with satellites in space were asked to take a look at the mysterious Voorwerp. The mystery thing is that object didn’t contain any stars. Rather, it was made entirely of gas so hot — about 10,000 Celsius — that the astronomers felt it had to be illuminated by something powerful. They will soon use the Hubble Space Telescope to get a closer look.

Since there was no obvious source at hand in the Voorwerp itself, scientist looked to find the source of illumination around the Voorwerp, and soon turned to the nearby galaxy IC 2497. It is thought that in the recent past the galaxy IC 2497 hosted an enormously bright quasar, a very unusual, highly luminous objects, powered by supermassive black holes, and most are extremely distant. Because of the vast scale of the galaxy and the Voorwerp, light from that past still lights up the nearby Voorwerp even though the quasar shut down sometime in the past 100,000 years, and the galaxy’s black hole itself has gone quiet. From the point of view of the Voorwerp, the galaxy looks as bright as it would have before the black hole turned off – it’s this light echo that has been frozen in time for us to observe!

(Picture credits: Dan Smith, Peter Herbert, Matt Jarvis / ING)

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Have you seen the picture of the Earth and its Moon taken from 31 million miles (49.8 million kilometers) away? Here it is:

This historic picture was taken by NASA’s Deep Impact spacecraft, as a part of the scientist’s effort to study alien worlds. It shows some specific features that are important for observations of Earth-like planets orbiting other stars.

During a full Earth rotation, images obtained by Deep Impact at a 15-minute cadence have been combined to make a color video. The final result is a video recording, shows the moon enters the frame (because of its orbital motion) and transits Earth, then leaves the frame.

Other spacecraft have imaged Earth and the moon from space, but Deep Impact is the first to show a transit of Earth with enough detail to see large craters on the moon and oceans and continents on Earth.

Deep Impact made history when the mission team directed an impactor from the spacecraft into comet Tempel 1 on July 4, 2005. NASA recently extended the mission, redirecting the spacecraft for a flyby of comet Hartley 2 on Nov. 4, 2010; on a mission called Deep Impact extended mission, or EPOXI.

The full Quicktime video is available here (1 MB), and a version using a near-infrared filter is here. Notice how much darker the Moon’s surface is than Earth’s — something we rarely see compared so well.

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A total solar eclipse will took place on August 01, 2008. The eclipse is visible from within a narrow corridor that traverses half the Earth. The path of the Moon’s umbral shadow begins in Canada and extends across northern Greenland, the Arctic, central Russia, Mongolia, and China where it will end at sunset. A partial eclipse is seen within the much broader path of the Moon’s penumbral shadow, which includes northeastern North America, most of Europe and Asia.

Eclipse starts at 09:23 UT. Greatest eclipse occurs at 10:21:07 UT (on latitude 65° 39′N, longitude 72° 18′E) when the axis of the Moon’s shadow passes closest to the centre of Earth. Maximum duration of totality is 2min 27s. Central eclipse ends at 11:20 UT. Over the course of 2 hours, the Moon’s umbra travels along a path approximately 10,200 km long and covers 0.4% of Earth’s surface area.

A live webcast from China can be seen on website http://www.exploratorium.edu/eclipse/.

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Recent study, published in the July 17 issue of Nature, shows that vast regions of the ancient highlands of Mars, which cover about half the planet, contain clay minerals, which can form only in the presence of water. Volcanic lavas buried the clay-rich regions during subsequent, drier periods of the planet’s history, but impact craters later exposed them at thousands of locations across Mars. The data for the study derives from images taken by the Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM, and other instruments on the NASA’s Mars Reconnaissance Orbiter.

Meanwhile, another study, published in the June 2 issue of Nature Geosciences, finds that the wet conditions on Mars persisted for a long time. Thousands to millions of years after the clays formed, a system of river channels eroded them out of the highlands and concentrated them in a delta where the river emptied into a crater lake slightly larger than California’s Lake Tahoe, approximately 25 miles in diameter. Now, the scientist turning the findings into a list of sites where future missions could land to look for organic chemistry and perhaps determine whether life ever existed on Mars!

In a color-enhanced image above, we can see the delta in a crater, named Jezero Crater, which once held a lake. Researchers report that ancient rivers ferried clay-like minerals (shown in green) into the lake, forming the delta. Clays tend to trap and preserve organic matter, making the delta a good place to look for signs of ancient life. (Picture credits: NASA/JPL/JHUAPL/MSSS/Brown University)

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Pluto and Eris now have a new counterpart. On July 11, 2008, the IAU/USGS Working Group on Planetary Nomenclature included Makemake (136472 Makemake) in the plutoid class, makes it officially both a dwarf planet and a plutoid, alongside the two previously known objects.

Discovered on March 31, 2005 by the team led by Michael Brown, the discovery was announced on July 29, 2005 on the same day as Eris. Previously known as “Easterbuny” (because of the discovery time shortly after Easter), the name “Makemake” (pronounced ma kay ma kay) stands for the creator of humanity in the mythos of the people of Easter Island. The name was chosen in part to preserve the object’s connection with Easter.

With opposition apparent magnitude of 16.7, Makemake is currently visually the second brightest Kuiper belt object after Pluto. This is bright enough to be visible using a high-end amateur telescope. The size of Makemake is not precisely known, but the detection in infrared by the Spitzer space telescope, combined with the similarities of spectrum with Pluto yielded an estimate of a 1,500 (+400/-200) km diameter, makes it the third largest known Trans-Neptunian object after Eris and Pluto.

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It is believed that the Moon was formed when a Mars-size body collided with Earth some 4.5 billion years ago. This “giant impact” melted both objects and sent molten debris into orbit around the Earth, some of which coalesced to form the Moon. Under this scenario, the heat from the giant impact would have vaporized the light elements.

Over the past forty years there have been significant efforts to determine the content and origin of the volatile contents in the lunar samples. There is reliable evidence that the Moon’s interior contains sulfur, some chlorine, fluorine, and carbon. Yet the evidence for indigenous H2O has remained elusive, consistent with the general consensus that the Moon is dry.

In a paper published in the July 10, 2008 issue of Nature, a team of researcher from Brown University, Carnegie Institution for Science, and Case Western Reserve University, reported that they have took advantage of new methods for analyzing lunar samples to detect tiny amounts of water. The newly developed techniques can detect extremely minute quantities of water in glasses and minerals by the technology called secondary ion mass spectrometry (SIMS). For the past four decades, the limit for detecting water in lunar samples was about 50 parts per million (ppm) at best, though with a new way to detect as little as 5 ppm of water, the scientists had really surprised to find a great deal more in these tiny glass beads, up to 46 ppm.

One glass bead told the tale of what happened. The researchers found that the volatiles decreased from the tiny sphere’s core to its rim—a difference that indicates that some 95% of the water was lost during the volcanic activity.

The researchers estimated that there was originally about 750 ppm of water in the magma at the time of eruption. Since the Moon was thought to be perfectly dehydrated, this is a giant leap from previous estimates. It suggests the intriguing possibility that the Moon’s interior might have had as much water as the Earth’s upper mantle. Though, the more intriguing question is: If the Moon’s volcanoes released 95% of their water, where did all that water go?

Since the Moon’s gravity is too feeble to retain an atmosphere, the researchers speculate that some of the water vapor from the eruptions was probably forced into space, but some may also have drifted toward the cold poles of the Moon where ice may be present in permanently shadowed craters. Several previous lunar missions have suggested the presence of ice at both poles. Unless it is very deep, lunar groundwater is unlikely to exist since the Sun heats most of the Moon’s surface to over 200°F (100°C).

Many scientists have believed the Moon’s polar ice, if there, originated from impacts of water-rich meteoroids and comets that struck the Moon’s surface over its history. The new study suggests that some of this water could have come from lunar volcanic eruptions. Verifying that water is at the Moon’s poles is one goal of the NASA Lunar Reconnaissance Orbiter mission, due to launch later this year. And it is the primary objective of the Lunar Crater Observation and Sensing Satellite with a 2009 launch date. Verification of water on the Moon’s surface is an important step in progress toward an eventual manned lunar outpost.

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