Jurij Gagarin - From up Here… the Earth is Beautiful
This new Hubble image is centered on NGC 5793, a spiral galaxy over 150 million light-years away in the constellation of Libra. This galaxy has two particularly striking features: a beautiful dust lane and an intensely bright center — much brighter than that of our own galaxy, or indeed those of most spiral galaxies we observe.
NGC 5793 is a Seyfert galaxy. These galaxies have incredibly luminous centers that are thought to be caused by hungry supermassive black holes — black holes that can be billions of times the size of the sun — that pull in and devour gas and dust from their surroundings. This galaxy is of great interest to astronomers for many reasons. For one, it appears to house objects known as masers. Whereas lasers emit visible light, masers emit microwave radiation. The term “masers” comes from the acronym Microwave Amplification by Stimulated Emission of Radiation. Maser emission is caused by particles that absorb energy from their surroundings and then re-emit this in the microwave part of the spectrum.
Naturally occurring masers, like those observed in NGC 5793, can tell us a lot about their environment; we see these kinds of masers in areas where stars are forming. In NGC 5793 there are also intense mega-masers, which are thousands of times more luminous than the sun.
Credit: NASA, ESA, and E. Perlman (Florida Institute of Technology)
In celebration of the 24th anniversary of the launch of NASA’s Hubble Space Telescope, astronomers have captured infrared-light images of a churning region of star birth 6,400 light-years away.
This colorful Hubble Space Telescope mosaic of a small portion of the Monkey Head Nebula unveils a collection of carved knots of gas and dust silhouetted against glowing gas. The cloud is sculpted by ultraviolet light eating into the cool hydrogen gas.
Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Apollo 8, the first manned mission to the moon, entered lunar orbit on Christmas Eve, Dec. 24, 1968. That evening, the astronauts-Commander Frank Borman, Command Module Pilot Jim Lovell, and Lunar Module Pilot William Anders-held a live broadcast from lunar orbit, in which they showed pictures of the Earth and moon as seen from their spacecraft. Said Lovell, “The vast loneliness is awe-inspiring and it makes you realize just what you have back there on Earth.” They ended the broadcast with the crew taking turns reading from the book of Genesis.
Image Credit: NASA
On Jan. 19, 2007, the Cassini spacecraft took this view of Saturn and its rings — the visible documentation of a technique called a “pi transfer” completed with a Titan flyby. A pi transfer uses the gravity of Saturn’s largest moon, Titan, to alter the orbit of the Cassini spacecraft so it can gain different perspectives on Saturn and achieve a wide variety of science objectives. During a pi transfer, Cassini flies by Titan at opposite sides of its orbit about Saturn (i.e., Titan’s orbital position differs by pi radians between the two flybys) and uses Titan’s gravity to change its orbital perspective on the ringed planet.
Taking in the rings in their entirety was the focus of this particular imaging sequence. Therefore, the camera exposure times were just right to capture the dark-side of its rings, but longer than that required to properly expose the globe of sunlit Saturn. Consequently, the sunlit half of the planet is overexposed.
The view is a mosaic of 36 images — that is, 12 separate sets of red, green and blue images — taken over the course of about 2.5 hours, as Cassini scanned across the entire main ring system. This view looks toward the unlit side of the rings from about 40 degrees above the ring plane.
The images in this natural-color view were obtained with the Cassini spacecraft wide-angle camera at a distance of approximately 1.23 million kilometers (764,000 miles) from Saturn. Image scale is 70 kilometers (44 miles) per pixel.
Image Credit: NASA/JPL/Space Science Institute
On Aug. 3, 2004, NASA’s Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft began a seven-year journey, spiraling through the inner solar system to Mercury. One year after launch, the spacecraft zipped around Earth, getting an orbit correction from Earth’s gravity and getting a chance to test its instruments by observing its home planet.
This image is a view of South America and portions of North America and Africa from the Mercury Dual Imaging System’s wide-angle camera aboard MESSENGER. The wide-angle camera records light at eleven different wavelengths, including visible and infrared light. Combining blue, red, and green light results in a true-color image from the observations. The image substitutes infrared light for blue light in the three-band combination. The resulting image is crisper than the natural color version because our atmosphere scatters blue light. Infrared light, however, passes through the atmosphere with relatively little scattering and allows a clearer view. That wavelength substitution makes plants appear red. Why? Plants reflect near-infrared light more strongly than either red or green, and in this band combination, near-infrared is assigned to look red.
Apart from getting a clearer image, the substitution reveals more information than natural color. Healthy plants reflect more near-infrared light than stressed plants, so bright red indicates dense, growing foliage. For this reason, biologists and ecologists occasionally use infrared cameras to photograph forests.
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Caption: Holli Riebeek
John Harris' illustration for the cover of A war of gifts, a novel by Orson Scott Card
First geologic map of Ganymede via @fadesingh
More details: Global Geologic Map of Ganymede by Geoffrey C. Collins, G. Wesley Patterson, James W. Head, Robert T. Pappalardo, Louise M. Prockter, Baerbel K. Lucchitta, and Jonathan P. Kay
This Chandra X-Ray Observatory image of the young star cluster NGC 346 highlights a heart-shaped cloud of 8 million-degree Celsius gas in the central region. Evidence from radio, optical and ultraviolet telescopes suggests that the hot cloud, which is about 100 light years across, is the remnant of a supernova explosion that occurred thousands of years ago.
The progenitor could have been a companion of the massive young star that is responsible for the bright X-ray source at the top center of the image. This young star, HD 5980, one of the most massive known, has been observed to undergo dramatic eruptions during the last decade. An alternative model for the origin of the hot cloud is that eruptions of HD 5980 long ago produced the cloud of hot gas, in a manner similar to the gas cloud observed around the massive star Eta Carinae. Future observations will be needed to decide between the alternatives. Until then, the nature of the heart in the darkness will remain mysterious.
Image Credit: NASA/CXC/U.Liege/Y.Nazé et al.