On April 17, the sky was clear and the Sun's colour was spectacular as night approached. This striking telescopic view even captures the Sun's swollen and distorted shape from the southern coast of the UK. Reflecting a bright column of sunlight, the sea also appears golden, with the horizon marked by the city of Portsmouth. Were the colours made more intense by volcanic dust? Maybe not. Normally, sunset (and sunrise) colours can be still be very dramatic, especially when the atmosphere is clear and the Sun is viewed very near the horizon, as in this scene. But large dust particles, like those in the airline thwarting ash clouds from the erupting Icelandic volcano Eyjafjallajökull, tend to create diffuse and subdued sunset colours.
Wednesday, April 28, 2010
Tuesday, April 27, 2010
In early April 2010, activity at Gaua Volcano in the Vanuatu Archipelago increased. The Vanuatu Geohazards Observatory reported that the ash column, which first appeared in October 2009, became thicker and higher (compare this image to one from February 14th), and volcanic bombs were frequently sighted from the coastal villages surrounding the volcano. According to Radio New Zealand International, Vanuatu government officials are preparing to evacuate residents of Gaua Island, who are threatened by ash, poisonous gases, and landslides.
The thick, stream-rich plume from Guau Volcano blows directly northeast in this natural-color satellite image. It was acquired on April 24, 2010 by the Advanced Land Imager aboard NASA’s Earth Observing-1 (EO-1) spacecraft. The thick steam is brighter white than the surrounding lower altitude clouds. Vegetation is green, as is Lake Letas. Vegetation to the south and west of the volcano, damaged by ash and acidic volcanic gases, is dark gray-brown.
- Global Volcanism Program. (2010, April 21). Weekly Reports: Gaua. Accessed April 26, 2010.
- Radio Australia News. (2010, April 23). Vanuatu authorities monitor Gaua volcano. Accessed April 26, 2010.
- Radio New Zealand International. (2010, April 19). Vanuatu prepares evacuation amid threats of Gaua volcano. Accessed April 26, 2010.
- Vanuatu Geohazards Observatory. (2010, April 7). Bulletin Number 3—Gaua Activity. Accessed April 26, 2010.
The series introduces young people to climate change and its potential impact on their families, their neighborhoods, and their national parks through guided exploration of changes occurring around the planet.
The new climate science learning experience begins at www.webrangers.us/activities/climate.
› WebRangers main page
"Investigating Global Connections" encourages children to examine changes occurring in a variety of locations, from coral reefs at Florida's Biscayne National Park to vanishing sea ice near Arctic coastal villages. As they progress through the activity, site visitors will also draw upon evidence of change provided by NASA images and satellite observations and draw conclusions about whether Earth is warming.
Children participating in this activity join more than 115,000 other registered WebRangers on the free, kid-friendly website. Site visitors who successfully complete all three climate science modules will earn one of 50 certificates required to obtain a Junior Ranger achievement patch and a personalized congratulatory letter in the mail.
"Change is happening," said Bob Bindschadler, an expert in polar research at NASA's Goddard Space Flight Center in Greenbelt, Md. "Through initiatives like this, kids will register a solid memory of what America's national parks look like now and will recognize -- and hopefully work to curb -- changes to their landscapes during their lifetimes."
Tom Davies, a Philadelphia-based National Park ranger who is program lead for WebRangers, believes NASA's space-based vantage point is essential to the value of the three-part series. "We're able to bring NASA's unique worldview to kids and grown-ups alike," said Davies.
Each activity in the WebRangers climate series also provides a downloadable climate change resource list, including links to NASA Web sites like Climate Kids, Earth Observatory, and Eyes on the Earth.
Development of the climate science WebRangers activities is an outgrowth of Earth to Sky, an ongoing partnership the three agencies started in 2004 to actively foster collaboration between the science and education communities linked to NASA and the Park Service.
"This activity links NASA's space-based views with natural and cultural resources found in parks and other protected landscapes," said Anita Davis, education and outreach coordinator for the Landsat Data Continuity Mission office at Goddard. "These connections bring real world relevance to the story of global change and, hopefully, also inspire children to consider careers in natural and physical sciences."
› WebRangers main page
› NASA's Earth Day site
› NASA's Climate Kids
› Global Climate Change: NASA's Eyes on the Earth
› NASA's Earth Observatory
› Earth Day Network
› The National Park Service
› NASA Education
NASA is developing and testing new and innovative technologies that will enable the future of safe and efficient human exploration.
Description: Pratt & Whitney Rocketdyne (PWR) and NASA successfully completed four deep throttling Common Extensible Cryogenic Engine (CECE) demonstrations, improving available cryogenic engine propulsion technology. The tests demonstrated that the engines could be throttled smoothly down to a new minimum power level of 5.9 percent of full power.
Time Frame: This work took place over five years, resulting in 123 minutes of engine run time with multiple rapid restarts.
Significance: Standard rocket engines typically cannot be throttled over a wide operating range because low power levels can cause engine pressure instability and possibly damage the engine or vehicle. Providing deep throttle capabilities can reduce the necessary amount of propellant, reducing the overall weight of the vehicle. A wide range of power variations may also allow soft surface landings for future missions.
Application: NASA plans to initiate several new technology and flight demonstration projects to improve capabilities, reduce costs and expand the reach of future human and robotic missions. This partnership with PWR exemplifies NASA’s goal to advance technological competition in the United States.
NASA is developing and testing new and innovative technologies that will enable the future of safe and efficient human exploration.
Description: NASA worked with MT Aerospace in Augsburg, Germany, to use their patented concave spin forming process and tooling to create new fuel tank domes. The process starts by friction stir welding (FSW) small metal plates together to create a large, unfinished metal plate known as a blank. This blank is then spin-formed to produce the dome. The single-piece, 5.5-meter-diameter dome shown was built from a 2195 aluminum-lithium (Al-Li) alloy blank.
Purpose: Because current commercially available plate sizes limit spin-formed dome scale, the objective is to mature FSW and spin-forming technologies and manufacturing processes. Ultimately, developing these techniques will enable creating larger, lighter and stronger fuel tanks.
Significance: Manufacturing a 5.5-meter dome demonstrates that spin-forming and FSW a high-strength aluminum alloy can produce a dome scaled up from the initial one-meter-diameter dome.
Next Steps: Develop the manufacturing process for future applications to other alloys and alternative architectures. This technology will benefit heavy lift launch vehicles, spacecraft, habitats and rovers.
What created this strange sound in Earth's Pacific Ocean? Pictured above is a visual representation of a loud and unusual sound, dubbed a Bloop, captured by deep sea microphones in 1997. In the above graph, time is shown on the horizontal axis, deep pitch is shown on the vertical axis, and brightness designates loudness. Although Bloops are some of the loudest sounds of any type ever recorded in Earth's oceans, their origin remains unknown. The Bloop sound was placed as occurring several times off the southern coast of South America and was audible 5,000 kilometers away. Although the sound has similarities to those vocalized by living organisms, not even a blue whale is large enough to croon this loud. The sounds point to the intriguing hypothesis that even larger life forms lurk in the unexplored darkness of Earth's deep oceans. A less imagination-inspiring possibility, however, is that the sounds resulted from some sort of iceberg calving. No further Bloops have been heard since 1997, although other loud and unexplained sounds have been recorded.
Monday, April 26, 2010
The Planck mission is busy surveying the whole sky at longer wavelengths of light than we can see with our eyes, ranging from infrared to even longer-wavelength microwaves. It is collecting ancient light, from the very beginning of time, to learn more about the birth and fate of our universe. In the process, the mission is gathering data on our Milky Way galaxy that astronomers are using to see through cold pools of gas and dust, which block visible-light views of star formation.
The new image is online at: http://www.nasa.gov/mission_pages/planck/planckorion20100426.html. It shows one such region in our Milky Way, where stars are actively bursting to life. The much-photographed Orion nebula is the bright spot to the lower center. The bright spot to the right of center is around the Horsehead Nebula, so called because at high magnifications a pillar of dust resembles a horse's head. The whole view covers a square patch of sky equivalent to 26 by 26 moons.
"Because Planck is mapping the whole sky, we can capture mosaics of huge regions of the Milky Way," said Charles Lawrence, the NASA project scientist for Planck at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We are seeing the coldest material in star-forming regions, where stars are at the very earliest stages of formation."
The giant red arc of Barnard's Loop is thought to be the blast wave from a star that blew up inside the region about two million years ago. The bubble it created is now about 300 light-years across.
The picture shows light resulting from two different types of radiation. At the lowest frequencies, Planck primarily maps emission from ionized gas heated by newly formed hot stars. At higher frequencies, Planck maps the meager heat emitted by extremely cold dust. This can reveal the coldest cores in the clouds, which are approaching the final stages of collapse, before they are reborn as full-fledged stars.
Another new image from Planck shows a similar, yet less vigorous star-forming area called Perseus. It is online at: http://www.nasa.gov/mission_pages/planck/planckperseus20100426.html .
Planck is a European Space Agency mission, with significant participation from NASA. NASA's Planck Project Office is based at JPL. JPL contributed mission-enabling technology for both of Planck's science instruments. European, Canadian, U.S. and NASA Planck scientists will work together to analyze the Planck data. More information is online at http://www.nasa.gov/planck and http://www.esa.int/planck .
NASA's Cassini spacecraft will be gliding low over Saturn's moon Enceladus for a gravity experiment designed to probe the moon's interior composition. The flyby, which will take Cassini through the water-rich plume flaring out from Enceladus's south polar region, will occur on April 27 Pacific time and April 28 UTC. At closest approach, Cassini will be flying about 100 kilometers (60 miles) above the moon's surface.
Cassini's scientists plan to use the radio science instrument to measure the gravitational pull of Enceladus against the steady radio link to NASA's Deep Space Network on Earth. Detecting any wiggle will help scientists understand what is under the famous "tiger stripe" fractures that spew water vapor and organic particles from the south polar region. Is it an ocean, a pond or a great salt lake?
The experiment will also help scientists find out if the sub-surface south polar region resembles a lava lamp. Scientists have hypothesized that a bubble of warmer ice periodically moves up to the crust and repaves it, explaining the quirky heat behavior and intriguing surface features.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.
Inside the head of this interstellar monster is a star that is slowly destroying it. The monster, on the right, is actually an inanimate pillar of gas and dust that measures over a light year in length. The star, not itself visible through the opaque dust, is bursting out partly by ejecting energetic beams of particles. Similar epic battles are being waged all over the star-forming Carina Nebula. The stars will win in the end, destroying their pillars of creation over the next 100,000 years, and resulting in a new open cluster of stars. The pink dots around the image are newly formed stars that have already been freed from their birth monster. The above image was released last week in commemoration of the Hubble Space Telescopes 20th year of operation. The technical name for the stellar jets are Herbig-Haro objects. How a star creates Herbig-Haro jets is an ongoing topic of research, but it likely involves an accretion disk swirling around a central star. A second impressive Herbig-Haro jet occurs diagonally near the image center.
Sunday, April 25, 2010
Saturday, April 24, 2010
Big, beautiful spiral galaxy NGC 1055 is a dominant member of a small galaxy group a mere 60 million light-years away toward the intimidating constellation Cetus. Seen edge-on, the island universe spans about 100,000 light-years, similar in size to our own Milky Way. Colorful, spiky stars in this cosmic portrait of NGC 1055 are in the foreground, well within the Milky Way. But along with a smattering of more distant background galaxies, the deep image also reveals a curious box-shaped inner halo extending far above and below this galaxy's dusty plane. The halo itself is laced with faint, narrow structures, and could represent the mixed and spread out debris from a satellite galaxy disrupted by the larger spiral some 10 billion years ago.
Friday, April 23, 2010
As the Hubble Space Telescope achieves the major milestone of two decades on orbit, NASA and the Space Telescope Science Institute, or STScI, in Baltimore are celebrating Hubble’s journey of exploration with a stunning new picture and several online educational activities. There are also opportunities for people to explore galaxies as armchair scientists and send personal greetings to Hubble for posterity.
NASA is releasing a new Hubble photo of a small portion of one of the largest known star-birth regions in the galaxy, the Carina Nebula. Three light-year-tall towers of cool hydrogen laced with dust rise from the wall of the nebula. The scene is reminiscent of Hubble’s classic “Pillars of Creation” photo from 1995, but even more striking.
NASA’s best-recognized, longest-lived and most prolific space observatory was launched April 24, 1990, aboard the space shuttle Discovery during the STS-31 mission. Hubble discoveries revolutionized nearly all areas of current astronomical research from planetary science to cosmology.
These two images of a three-light-year-high pillar of star birth demonstrate how observations taken in visible and infrared light by NASA's Hubble Space Telescope reveal dramatically different and complementary views of an object.
Over the years, Hubble has suffered broken equipment, a bleary-eyed primary mirror, and the cancellation of a planned shuttle servicing mission. But the ingenuity and dedication of Hubble scientists, engineers and NASA astronauts allowed the observatory to rebound and thrive. The telescope's crisp vision continues to challenge scientists and the public with new discoveries and evocative images.
"Hubble is undoubtedly one of the most recognized and successful scientific projects in history," said Ed Weiler, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "Last year's space shuttle servicing mission left the observatory operating at peak capacity, giving it a new beginning for scientific achievements that impact our society."
Hubble fans worldwide are being invited to take an interactive journey with Hubble. They can also visit Hubble Site to share the ways the telescope has affected them. Follow the “Messages to Hubble” link to send an e-mail, post a Facebook message, or send a cell phone text message. Fan messages will be stored in the Hubble data archive along with the telescope’s science data. For those who use Twitter, you can follow @HubbleTelescope or post tweets using the Twitter hashtag #hst20.
This is a series of close-up views of the complex gas structures in a small portion of the Carina Nebula. The nebula is a cold cloud of predominantly hydrogen gas. It is laced with dust, which makes the cloud opaque. The cloud is being eroded by a gusher of ultraviolet light from young stars in the region. They sculpt a variety of fantasy shapes, many forming tadpole-like structures. In some frames, smaller pieces of nebulosity can be seen freely drifting, such as the 2.3-trillion-mile-long structure at upper right. The most striking feature is a 3.5- trillion-mile-long horizontal jet in the upper left frame. It is being blasted into space by a young star hidden in the tip of the pillar-like structure. A bowshock has formed near the tip of the jet.
The public also will have an opportunity to become at-home scientists by helping astronomers sort out the thousands of galaxies seen in a Hubble deep field observation. STScI is partnering with the Galaxy Zoo consortium of scientists to launch an Internet-based astronomy project where amateur astronomers can peruse and sort galaxies from Hubble’s deepest view of the universe into their classic shapes: spiral, elliptical, and irregular. Dividing the galaxies into categories will allow astronomers to study how they relate to each other and provide clues that might help scientists understand how they formed.
To visit the Galaxy Zoo page, go to http://www.hubble.galaxyzoo.org.
For educators and students, STScI is creating an educational website called “Celebrating Hubble’s 20th Anniversary." It offers links to facts and trivia about Hubble, a news story that chronicles the observatory’s life and discoveries, and the IMAX “Hubble 3D” educator's guide. An anniversary poster containing Hubble’s “hall-of-fame” images, including the Eagle Nebula and Saturn, also is being offered with downloadable classroom activity information.
Visit the website at http://amazing-space.stsci.edu/hubble_20.
To date, Hubble has observed more than 30,000 celestial targets and amassed more than a half-million pictures in its archive. The last astronaut servicing mission to Hubble in May 2009 made the telescope 100 times more powerful than when it was launched.
For Hubble 20th anniversary image files and more information, visit http://hubblesite.org/news/2010/13 or http://www.spacetelescope.org/news/html/heic1007/.
Hubble, named for groundbreaking astronomer Edwin Hubble, repaid the commitment with some of the most dazzling images the world has seen, along with fresh data that answered a wealth of questions and led to many new ones. The telescope's observations allowed astronomers to set the age of the universe at about 13.7 billion years with a high degree of certainty.
"I never believed in 1990 that the Hubble would end up this great," said Ed Weiler, NASA associate administrator for the Science Mission Directorate and chief scientist for the Hubble program when it launched. "It's changed a lot of thinking and it's changed a lot of what I learned 30 years ago in grad school."
Hubble's discoveries stretch over most aspects of astronomy, but its highlights include proving massive black holes exist and defining the age of the universe. It also proved the existence of something no one has seen -- dark energy.
"Nobody ever knew it existed before Hubble," said Jon Grunsfeld, an astronaut and astronomer who worked on Hubble during two shuttle missions.
The telescope's most unique element, though, is its orbit -- a perch so high above the planet that its pictures are not warped or distorted by the air currents, moisture and other effects from Earth's atmosphere.
"It's that extreme clarity that gives us the feeling we've traveled out into space to see these objects," Grunsfeld said. "It really is our time machine."
From more than 300 miles in space, Hubble looked back in time, showing astronomers what embryonic galaxies looked like almost 14 billion years ago. In some cases, Hubble's instruments picked up light that left stars only 600 million years after the Big Bang. "We're seeing the universe as it was perhaps as a toddler," Grunsfeld said.
An image that is perhaps Hubble's most famous, known as the Hubble Deep Field, was made when the telescope was pointed at a small sliver of space in the constellation Ursa Major, which appeared black and empty. Hubble found it brimming with young galaxies and stars in a kind of photographic time capsule from the universe. Astronomers called it a baby picture of space.
The Hubble Ultra Deep Field built on that image in 2003 and 2004 when it used new instruments to pick out galaxies in another section of the sky which would have been too faint for Hubble's previous equipment to detect.
"We always discover things that we never even imagine," Grunsfeld said. "The universe is always more interesting than we give it credit for."
Some of the most notable discoveries were almost lost because Hubble was launched with a tiny flaw in its main mirror. Although the mirror was ground too flat by less than the width of a human hair, that was enough to throw off the focus.
"Little did we know we were launching a telescope that had a mirror that was slightly misshapen," Weiler said. "But we found a way to fix it, which we did, which the astronauts did, in 1993 and for the past 17 years Hubble's been filling the textbooks with new science." Starting with STS-61 in 1993, five teams of astronauts worked on the telescope from the space shuttle. The first installed a set of small mirrors that acted like a contact lens to clarify Hubble's vision. Since then, new instruments have been added, along with new components. Taken together, the servicing missions added years to Hubble's life.
"When we launched it in 1990, we were hoping to get 10 to 15 years out of it," Weiler said. "We're now talking about the 20th anniversary, so we're talking about five years of dividends on our investment, and we should be able to get at least another five years and maybe another seven, eight or nine years."
Astronomers were not the only ones pleased with the life extension. The 12 1/2-ton space telescope reached into the mind and spirit of the general public in an unprecedented way. Images from the telescope have made their way onto stamps, album covers and even into art exhibits.
"I think the unique thing about the Hubble is that it's truly brought science to the general public, especially the school kids," Weiler said. "It's still the most powerful telescope that humans have the ability to use and it has been since it was launched."As much as Hubble became a cornerstone for astronomy, it was also the first element of NASA's Great Observatories program which produced four telescopes that looked at the different kinds of light in the universe. The Hubble was designed to see visible light, which is the same light people see. So Hubble's pictures show the universe as it appears to the human eye.
The Compton Gamma Ray Observatory launched in 1991 to detect gamma ray bursts, some of the most energetic particles known. The Chandra X-Ray Observatory was launched in 1999 and surveyed the universe for invisible x-rays. Lastly, the Spitzer Space Telescope went into space in 2003 to look at the cooler heart of space, including dust clouds that are the nursery for stars. The Spitzer was the only NASA “Great Observatory” not launched on a shuttle. Instead, it rode a Delta II.
None of the observatories was meant to study space by themselves. Astronomers instead used one telescope's findings to study it with the others to form a nearly complete picture of a celestial place across the spectrum of light. Ground-based telescopes, which continue to grow in size and sophistication, are also used to study or confirm findings.
Although there won't be any more servicing missions by the shuttle, Weiler and Grunsfeld said the telescope is ready to make more discoveries.
"The telescope still looks in great shape," Grunsfeld said. "It's just a thrill to work on what is by many measures the most productive scientific instrument ever created by humans."
Don't panic, the Sun has not gone wild. But this wild-looking portrait of the nearest star to planet Earth was made on March 30th by the recently launched Solar Dynamics Observatory (SDO). Shown in false-color, the composite view covers extreme ultraviolet wavelengths and traces hot plasma at temperatures approaching 1 million kelvins. At full resolution, SDO image data is intended to explore solar activity in unprecedented detail. In fact, SDO will send 1.5 terabytes of data back each day, equivalent to a daily download of about half a million MP3 songs. New SDO data releases include a high-resolution movie of the large, eruptive prominence seen along the solar limb at the upper left.
Thursday, April 22, 2010
Earlier this month, Venus and Mercury climbed into the western twilight, entertaining skygazers around planet Earth in a lovely conjunction of evening stars. Combining 8 images spanning April 4 through April 15, this composite tracks their progress through skies above Portsmouth, UK. Each individual image was captured at 19:50 UT. The sequential path for both bright planets begins low and to the left. But while Venus continues to swing away from the setting Sun, moving higher above the western horizon, Mercury first rises then falls. Its highest point is from the image taken on April 11. Of course on April 15, Venus and Mercury were joined by a young crescent Moon.
Wednesday, April 21, 2010
Nebulae are perhaps as famous for being identified with familiar shapes as perhaps cats are for getting into trouble. Still, no known cat could have created the vast Cat's Paw Nebula visible in Scorpius. At 5,500 light years distant, Cat's Paw is an emission nebula with a red color that originates from an abundance of ionized hydrogen atoms. Alternatively known as the Bear Claw Nebula or NGC 6334, stars nearly ten times the mass of our Sun have been born there in only the past few million years. Pictured above, a wide angle, deep field image of the Cat's Paw nebula was culled from the second Digitized Sky Survey.
Tuesday, April 20, 2010
What would it be like to see a sky with many moons? Such is the sky above Saturn. When appearing close to each other, moons will show a similar phase. A view with two of the more famous moons of Saturn in gibbous phase was captured last month by the robot spacecraft Cassini now orbiting Saturn. Titan, on the left, is among the largest moons in the Solar System and is perpetually shrouded in clouds. In 2005, the Huygens probe landed on Titan and gave humanity its first view of its unusual surface. Dione, on the right, has less than a quarter of Titan's diameter and has no significant atmosphere. The above uncalibrated image was taken on April 10 after Cassini swooped by each moon the previous week.
Monday, April 19, 2010
Why did the recent volcanic eruption in Iceland create so much ash? Although the large ash plume was not unparalleled in its abundance, its location was particularly noticeable because it drifted across such well populated areas. The Eyjafjallajökull volcano in southern Iceland began erupting on March 20, with a second eruption starting under the center of a small glacier on April 14. Neither eruption was unusually powerful. The second eruption, however, melted a large amount of glacial ice which then cooled and fragmented lava into gritty glass particles that were carried up with the rising volcanic plume. Pictured above two days ago, lightning bolts illuminate ash pouring out of the Eyjafjallajökull volcano.
Sunday, April 18, 2010
What's happened to our Sun? Last week, it produced one of the largest eruptive prominences ever seen. Pictured above, the prominence erupted in only a few hours and was captured in movie form by NASA's twin Sun-orbiting STEREO satellites. A quiescent solar prominence is a cloud of hot solar gas held above the Sun's surface by the Sun's magnetic field. Unpredictably, however, prominences may erupt, expelling hot gas into the Solar System via a Coronal Mass Ejection (CME). As pictured above, many Earths would easily fit under the expanding ribbon of hot gas. Although somehow related to the Sun's changing magnetic field, the energy mechanism that creates and sustains a Solar prominence is still a topic of research.
Saturday, April 17, 2010
After an oxygen tank exploded and crippled their service module, the Apollo 13 astronauts were forced to abandon plans to make the third manned lunar landing. The extent of the damage is revealed in this grainy, grim photo, taken as the service module was drifting away, jettisoned only hours prior to the command module's reentry and splashdown. An entire panel on the side of the service module has been blown away and extensive internal damage is apparent. Visible below the gutted compartment is a radio antenna and the large, bell-shaped nozzle of the service module's rocket engine. On April 17, 1970 the three astronauts returned safely to Earth.
Friday, April 16, 2010
Up close, the solar surface is a striking patch work of granules in this very high resolution picture of the quiet Sun. Caused by convection, the granules are hot, rising columns of plasma edged by dark lanes of cooler, descending plasma. But the high-resolution view reveals that the dark lanes are dotted with many small, contrasting bright points. Constantly present on the solar surface, the bright points do not seem to be related to sunspots that come and go with the magnetic solar cycle. Nonetheless, the bright points are regions of concentrated magnetic fields and are bright because the magnetic pressure opens a window to hotter deeper layers below the photosphere. For scale, the white bar at the lower left corresponds to 5,000 kilometers across the Sun's surface. The sharp, narrow-band image was recorded in September, 2007 using the Swedish Solar Telescope on the astronomical island of La Palma.
Thursday, April 15, 2010
Spiral galaxy NGC 4651 is a mere 35 million light-years distant, toward the well-groomed constellation Coma Berenices. About 50 thousand light-years across, this galaxy is seen to have a faint umbrella-shaped structure (right) that seems to extend some 50 thousand light-years farther, beyond the bright galactic disk. The giant cosmic umbrella is now known to be composed of tidal star streams. The streams themselves are extensive trails of stars gravitationally stripped from a smaller satellite galaxy that was eventually torn apart. Placing your cursor over the image will superimpose a simulation of the satellite galaxy's path as it was disrupted and absorbed into NGC 4651. Recent work by a remarkable collaboration of amateur and professional astronomers to image faint structures around bright galaxies suggests that even in nearby galaxies, such tidal star streams are common. The result is predicted by models of galaxy formation, including the formation of our Milky Way.