The aurora australis seen from the ISS on September 17, 2011. Credit: NASA.
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With all of the activity that’s been occurring on the Sun recently, the aurorae have been exceptionally bright and have created quite a show to viewers – both on Earth as well as above it!
The image above was taken over the southern Indian Ocean by astronauts aboard the International Space Station. The southern lights – a.k.a. aurora australis – glow bright green and red in the upper layers of the atmosphere, creating a dazzling aerial display. (Click here to watch a movie of this.)
Shortly after, fires can be seen on the ground as the ISS passes over Australia:
Wildfires in Australia seen from orbit. Credit: NASA.
Astronauts on the International Space Station (ISS) used a digital camera to capture several hundred photographs of the aurora australis, or “southern lights,” while passing over the Indian Ocean on September 17, 2011. You can see the flowing ribbons and rays below as the ISS passed from south of Madagascar to just north of Australia between 17:22 and 17:45 Universal Time. Solar panels and other sections of the ISS fill some of the upper right side of the photograph.
Auroras are a spectacular sign that our planet is electrically and magnetically connected to the Sun. These light shows are provoked by energy from the Sun and fueled by electrically charged particles trapped in Earth’s magnetic field, or magnetosphere. In this case, the space around Earth was stirred up by an explosion of hot, ionized gas from the Sun — a coronal mass ejection — that left the Sun on September 14, 2011.
In the second image above, and in the last frames of the movie, light from the ground replaces the light show in the sky. Wildfires and perhaps some intentionally set agricultural fires burn on the continent of Australia,with smoke plumes faintly visible in the night sky. A gold and green halo of atmospheric airglow hangs above the horizon in the distance.
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Airglow is created by particles in the upper atmosphere that have been charged by UV light from the Sun during the day releasing the energy at night as greenish-yellow visible light.
Fires on the ground, fires in the sky… the stars blazing all around, the Sun in its full glory and a never-ending view of our entire planet… what an incredible place the ISS must be to work in! Absolutely amazing!
And the skies of night were alive with light, with a throbbing, thrilling flame; Amber and rose and violet, opal and gold it came. It swept the sky like a giant scythe, it quivered back to a wedge; Argently bright, it cleft the night with a wavy golden edge.
— “The Ballad of the Northern Lights”, Robert Service
Planet Mercury as seen from the MESSENGER spacecraft in 2008. Credit: NASA/JPL
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According to data from the The Fast Imaging Plasma Spectrometer (FIPS) onboard NASA’s MESSENGER spacecraft, the solar wind is “sandblasting” the surface of Mercury at its polar regions.
Based on findings from one of seven different papers from the MESSENGER mission to be published in the Sept. 30th edition of Science, sodium and oxygen particles are charged in a manner similar to Earth’s own Aurora Borealis.
How are the University of Michigan researchers able to detect and study this phenomenon?
Using the FISP, the scientists at the University of Michigan have taken measurements of Mercury’s exosphere and magnetosphere. The data collected has provided researchers with a better understanding of interactions between Mercury and our Sun. FIPS data has also confirmed theories regarding the composition and source of particles in Mercury’s space environment.
“We had previously observed neutral sodium from ground observations, but up close we’ve discovered that charged sodium particles are concentrated near Mercury’s polar regions where they are likely liberated by solar wind ion sputtering, effectively knocking sodium atoms off Mercury’s surface,” said FIPS project leader Thomas Zurbuchen (University of Michigan).
In a UM press release, Zurbuchen added, “We were able to observe the formation process of these ions, and it’s comparable to the manner by which auroras are generated in Earth’s atmosphere near polar regions.”
Given that Earth and Mercury are the only two magnetized planets in the inner solar system (Mars is believed to have had a magnetic field in its past), the solar wind is deflected around them. The solar wind has made recent news due to recent outbursts from the Sun causing visible aurorae, caused by the interaction of charged particles from the Sun and Earth’s relatively strong magnetosphere. While Mercury does have a magnetosphere, compared to Earth’s it is relatively weak. Given Mercury’s weak magnetosphere and close proximity to the Sun, the effects of the solar wind have a more profound effect.
The Fast Imaging Plasma Spectrometer on board MESSENGER has found that the solar wind is able to bear down on Mercury enough to blast particles from its surface into its wispy atmosphere. Image Credit: Shannon Kohlitz, Media Academica, LLC
“Our results tell us is that Mercury’s weak magnetosphere provides very little protection of the planet from the solar wind,” Zurbuchen said.
Jim Raines, FIPS operations engineer (University of Michigan) added, “We’re trying to understand how the sun, the grand-daddy of all that is life, interacts with the planets. It is Earth’s magnetosphere that keeps our atmosphere from being stripped away. And that makes it vital to the existence of life on our planet.”
A high-resolution monochrome image has been combined with a lower-resolution enhanced-color image. The hollows appear in cyan, a result of their high reflectance and bluish color relative to other parts of the planet. The large pit in the center of the crater may be a volcanic vent, from which the orange material erupted. Credit: Courtesy of Science/AAAS
The MESSENGER team also released other results from the mission, including new evidence that flood volcanism has been widespread on Mercury, the first close-up views of Mercury’s “hollows,” and the first direct measurements of the chemical composition of Mercury’s surface.
MESSENGER, as well the the Mariner 10 flyby mission saw unusual features on the floors and central mountain peaks of some impact craters which were very bright and have a blue color relative to other areas of Mercury. This type of feature is not seen on the Moon, and were nicknamed “hollows.”
Now, with the latest MESSENGER data, hollows have been found over a wide range of latitudes and longitudes, suggesting that they are fairly common across Mercury. Many of the depressions have bright interiors and halos.
“To the surprise of the science team, it turns out that the bright areas are composed of small, shallow, irregularly shaped depressions that are often found in clusters,” says David Blewett, a staff scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and lead author of one of the Science reports. “The science team adopted the term ‘hollows’ for these features to distinguish them from other types of pits seen on Mercury.”
Blewett added the hollows detected so far have a fresh appearance and have not accumulated small impact craters, indicating that they are relatively young.
A Long March-2FT1 carrier rocket loaded with Tiangong-1 unmanned space lab module blasts off from the launch pad at the Jiuquan Satellite Launch Center in northwest China's Gansu Province, Sept. 29, 2011. (Xinhua/Wang Jianmin)
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China launched their first space station module into orbit today (Sept. 29), marking a major milestone in the rapidly expanding Chinese space program. The historic liftoff of the man ratedTiangong 1 (Heavenly Palace 1) space lab on a Long March 2F rocket took place at 9:16 p.m. local time (9:16 a.m. EDT) from the Jiuquan Satellite Launch Center located in Gansu province in northwest China and is an impressive advance for China.
The beautiful nighttime liftoff occurred exactly on time and was carried live on China’s state run television – CCTV – and on the internet for all to see. Chinese President Hu Jintao and many of China’s other top government leaders witnessed the launch from the Beijing Aerospace Control Center as a gesture of confidence and support. Their presence was a clear sign of just how important China’s top leadership considers investments in research as a major driver of technological innovation that is bolstering China’s vigorously growing economy and employing tens of thousands of people.
The US – in sharp contrast – is cutting space spending and handing out pink slips to many thousands of shuttle workers, CCTV noted.
As a CCTV commentator said after the successful Tiangong 1 launch, “30 Years ago it was ‘science fiction’ to imagine a Chinese astronaut in space. Today it’s a reality!”
Long range cameras tracked rocket for several minutes and clearly showed the jettisoning of the first stage boosters and the payload fairing.
“The launch of Tiangong 1 has been successfully completed,” announced Gen. Chang Wanquan, chief commander of China’s manned space engineering project on CCTV
Liftoff of March 2F rocket with Tiangong 1 space lab on Sept. 29, 2011. Credit: CCTV
Tiangiong 1 will serve a crucial role as a docking target to carry out China’s first rendezvous and docking in space- initially with an unmanned vehicle and thereafter with astronauts crews. The US and the Soviet Union mastered these technologies back in the 1960’s, and China is rapidly catching up now.
Rendezvous and docking are key accomplishments that China must achieve in order to move forward and accomplish even more ambitious space goals – construction of a 60 ton space station by the year 2020.
The two stage Long March 2F rocket was upgraded with more than 170 improvements including a larger payload fairing to house bigger Tiangong 1 module, four longer liquid fueled strap on boosters with more powerful thrust capability and more precise guidance systems.
The 8.5 ton Tiangong 1 was designed to stay in space for at least 2 years and support crews of up to three astronauts for short duration stays. It will be the target of at least three upcoming space missions – Shenzhou 8, 9 and 10.
China’s Long March 2F rocket blasts Tiangong 1 to orbit on Sept. 29, 2011. Credit: CCTV
Shenzhou is China’s human spaceflight capsule, derived from the Russian Soyuz and also significantly upgraded with China’s own nationally developed technology.
The unmanned Shenzhou 8 will launch in about 1 month according to officials from the China Manned Space Engineering Office and reach the vicinity of Tiangong 1 after 2 days. Shenzhou 8 will conduct at least two practice test dockings to extensively check out all systems and experience.
Shenzhou 9 and 10 will dock during 2012 and are likely to include the first female Chinese astronaut.
Tiangong 1 is a prototype miniture space station module, not fully outfitted for long duration stays of astronauts. The space lab consists of two segments – a forward habitable, pressurized section for the astronauts (measuring some 530 cubic feet in volume) and an unpressurized resource compartment in the rear with two solar arrays consisting of four segments to provide ample power.
Historic liftoff of China’s first man rated Tiangong 1 space module atop a Long March 2F rocket on Sept. 29, 2011 at 9:16 p.m. local time from the Jiuquan Satellite Launch Center, Gansu province, China. Credit: CCTV
With NASA’s announcement of its new, mammoth Space Launch System (SLS), preparations can begin in earnest for the first human mission to an asteroid. The SLS will take the Orion Multipurpose Crew Vehicle (MPCV) on the first human forays into deep space, out of the Earth/Moon system. “We are definitely excited about it,” Laurence Price, Lockheed Martin’s Orion deputy program manager told Universe Today during a briefing last week. “It is very good to get this baselined and be able to move forward.”
Lockheed Martin has been working on the Orion MPCV, which was originally part of the Constellation program to return to the Moon. But NASA has now been given a presidential directive to land astronauts on an asteroid by 2025, a mission that some say represents the most ambitious and audacious plan yet for the space agency. Orion will likely be re-worked and updated for potential “stepping stone” missions that will take humans to possible destinations such as lunar orbit, the Lagrange points, asteroids, and potentially the moons of Mars. The ultimate destination on this path is to send humans to the Red Planet.
Stepping stone destinations on the way to Mars. Credit: Lockheed Martin.
Billed as the biggest rocket ever built, the first incarnation of NASA’s SLS heavy-lift booster — which was unveiled on Sept. 14, 2011 — will stand over 30 stories tall, have a mass of 2.5 million kg (5.5 million pounds) and use a liquid hydrogen and liquid oxygen propulsion system, with 5 space shuttle main engines and an improved J-2X engine for the upper stage. (NASA just tested one of those engines). The SLS will have an initial lift capacity of 70 metric tons (mT), or about 69,853 kg (154,000 pounds) of payload into low Earth orbit. For reference, that’s more than double the lift capacity of any current launch vehicle, and it is estimated to be able to generate 10% more thrust than the Saturn 5 rockets produced at liftoff, the launchers that sent the Apollo missions to the Moon.
Later, to send the Orion and a service module out into space, the SLS would add two more RD-25D/E engines on the first stage, and the “evolved” architecture would be able to lift 130 metric tons, or 129,727 kg (286,000 pounds) of mass to low Earth orbit. This would increase the mass of the stack to 2.6 million kg (6.5 million pounds) and it would stand as tall as a 40-story building. This configuration would enable thrust of 4.2 million kg (9.2 million pounds), 20% more than the Saturn 5.
But Lockheed Martin is still in the initial stages of learning about the capabilities and timelines of the new launch system so they can produce the best version of Orion to pair with the SLS.
“While there are some challenges,” Price said, “we have been looking at various configurations of the architecture over the past year, so a lot of work has already been going on. So, any of the initial challenges, we have already worked toward mitigating.”
There are several differences between SLS and Constellation, Price said, with SLS having potentially a liquid booster with solid strap-ons instead of a solid first stage. “But we’ve been flying in space for 50 years and all the analytical tools to predict the environments, flight trajectories and flight conditions are all fairly straightforward, and we’re working to close on it. The launch vehicle design change is not a big perturbation on our ability to continue to mature the vehicle.”
In factoring the capability of how much mass the SLS can launch to deep space, Lockheed Martin can begin to work on how they would manifest the various parts of the mission.
“For example, would we launch the two spacecraft together on one rocket,” said Josh Hopkins from Lockheed Martin, in an interview with Universe Today, “and like Apollo, go to deep space quickly, or would we do what Constellation was planning, where you’d launch the larger pieces on the heavy lift vehicle and launch the crew separately on a second launch and connect them in Earth orbit?”
Hopkins is the Principal Investigator for Advanced Human Exploration Missions at Lockheed Martin, and leads a team of engineers who develop plans and concepts for a variety of future human exploration missions, including visits to asteroids.
The Orion casule in an Acoustic Chamber for testing at Lockheed Martin. Credit: Lockheed Martin
“If the two are launched separately,” Hopkins continued, “then you’d have to allocate a few days in orbit to have the two hook up, or one scrubbed launch could ruin the attempt. So those are the top level kinds of things we are looking forward to finding out from NASA. At the detailed level, we’re working on things like what the flight environments will be like, how much load will the spacecraft see. What we’ve inferred from the studies we’ve been doing is that we think that Orion is already designed to a pretty rigorous set of acoustics, dynamic pressure and G-loads during ascent.”
“We already know a lot about this vehicle, its environment, load conditions and trajectory,” Price said, “so we are accommodating the unique capability of the launch vehicle into the design of the Orion MPCV. We are already converging on how this vehicle will fly, and as soon as possible, we will transition to flying our test flights on early versions of the SLS.”
Lockheed Martin is targeting late 2013 or early 2014 for their first flight test of the Orion MPCV and they have reserved a Delta 4 Heavy for an unpiloted launch from Kennedy Space Center, but they are still evaluating what launcher would be best.
“We are identifying what the best test booster will be,” Price said, “and are trying to maximize the benefit to both programs, the launch system maturation and our spacecraft.”
An artist's concept shows the Orion Multipurpose Crew Vehicle and future destinations for human exploration beyond Earth orbit: the moon, an asteroid and Mars. Credit: NASA
As far as actually sending humans to an asteroid, there are many details to be worked out, and NASA and Lockheed Martin must allow for all the unknowns of flying humans in deep space, including a very important one of making sure humans can endure the radiation environment in space.
Hopkins said the robotic spacecraft that have flown to asteroids and Mars have tested the environment of deep space. “So, we have elegant models of how to design systems to withstand radiation shielding,” he said, “even though we don’t know the effect of deep space radiation on people, and what the environments around small asteroids actually like.” Hopkins added that redundant systems for keeping humans safe are an integral part of Orion’s design, but NASA might also first send a robotic scout mission to visit an asteroid.
Yes, there’s much to be worked out to actually send humans to an asteroid. But one initial item of importance is knowing the timing of when SLS will be ready to do a human deep space mission, as that would determine what asteroids we’d be able to go to.
And finding an asteroid that is just right is going to be a challenge, too. We’ll discuss that in the next in our series of articles on a human asteroid mission.
Here’s a new image for the Where In The Universe Challenge, to test your visual knowledge of the cosmos. You know what to do: take a look at this image and see if you can determine where in the universe this image is from; give yourself extra points if you can name the spacecraft/telescope responsible for the image. We’ll provide the image today, but won’t reveal the answer until later. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.
This is a a near-infrared image of lower-level clouds on the night side of Venus, taken by the Galileo spacecraft’s Near Infrared Mapping Spectrometer, taken as the spacecraft flew by Venus on February 10, 1990, as it was wending its way towards Jupiter. You can learn more about his image at JPL’s Photojournal.
In our last thrilling cliff hanger, we talked about astronomer superhero Galileo Galilei. Will a mission be named after him? The answer is yes! NASA’s Galileo spacecraft visited Jupiter in 1995, and spent almost 8 years orbiting, changing our understanding of the giant planet and its moons.
NASA announces student Essay Naming Contest for the twin GRAIL Lunar spaceships. The essay writing contest is open to students in Grades K - 12 at schools in the United States. Submission Deadline is November 11, 2011. GRAIL A & B are twin science robots that will explore the gravity field of the moon like never before.
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Student Alert ! – Here’s your once in a lifetime chance to name Two NASA robots speeding at this moment to the Moon on a super science mission to map the lunar gravity field. They were successfully launched from the Earth to the Moon on September 10, 2011. Right now the robots are called GRAIL A and GRAIL B. But, they need real names that inspire. And they need those names real soon. The goal is to “capture the spirit and excitement of lunar exploration”, says NASA – the US Space Agency.
NASA needs your help and has just announced an essay writing contest open to students in Grades K – 12 at schools in the United States. The deadline to submit your essay is November 11, 2011. GRAIL stands for “Gravity Recovery And Interior Laboratory.”
The rules state you need to pick two names and explain your choices in 500 words or less in English. Your essay can be any length up to 500 words – even as short as a paragraph. But, DO NOT write more than 500 words or your entry will be automatically disqualified.
Learn more about the GRAIL Essay Naming Contest here:
Students: NASA Wants You to Name that GRAIL !
Write an Essay and name these twin Lunar mapping satellites. NASA’s twin GRAIL A & B science probes are now streaking to the Moon and arrive on New Year’s Day 2012. This picture shows how they looked, mounted side by side, during launch preparations prior to blasting off for the Moon on Sept. 10, 2011 from Florida. Credit: Ken Kremer
The GRAIL A and B lunar spaceships are twins – just like those other awe inspiring robots “Spirit” and “Opportunity” , which were named by a 10 year old girl student and quickly became famous worldwide and forever because of their exciting science missions of Exploration and Discovery.They arrive in Lunar Orbit on New Year’s Day 2012.
Blastoff of twin GRAIL A and B lunar gravity mapping spacecraft on a Delta II Heavy rocket on Sept. 10 from Pad 17B Cape Canaveral Air Force Station in Florida at 9:08 a.m. EDT. Credit: Ken Kremer
And there is another way that students can get involved in NASA’s GRAIL mission.
GRAIL A & B are both equipped with four student-run MoonKAM cameras. Students can suggest targets for the cameras. Then the cameras will take close-up views of the lunar surface, taking tens of thousands of images and sending them back to Earth.
“Over 1100 middle schools have signed up to participate in the MoonKAM education and public outreach program to take images and engage in exploration,” said Prof. Maria Zuber of MIT.
Prof. Zuber is the top scientist on the mission and she was very excited to announce the GRAIL Essay Naming contest right after the twin spaceships blasted off to the Moon on Sep 10, 2011 from Cape Canaveral in Florida.
What is the purpose of GRAIL ?
“GRAIL simply put, is a ‘Journey to the Center of the Moon’,” says Dr. Ed Weiler, NASA Associate Administrator of the Science Mission Directorate in Washington, DC.
“It will probe the interior of the moon and map its gravity field by 100 to 1000 times better than ever before. We will learn more about the interior of the moon with GRAIL than all previous lunar missions combined. Precisely knowing what the gravity fields are will be critical in helping to land future human and robotic spacecraft. The moon is not very uniform. So it’s a dicey thing to fly orbits around the moon.”
“There have been many missions that have gone to the moon, orbited the moon, landed on the moon, brought back samples of the moon,” said Zuber. “But the missing piece of the puzzle in trying to understand the moon is what the deep interior is like.”
So, what are you waiting for.
Start thinking and writing. Students – You can be space explorers too !
Image of Venus in ultraviolet light by ESA's Venus Express.
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Venus, Earth’s hotheaded neighbor, may have more variability in its weather patterns than previously believed. Using infrared data obtained by ground-based telescopes in Hawaii and Arizona researchers have found that Venus’ mesosphere and thermosphere are less consistent in temperature than layers closer to its surface.
But first let’s talk about Venus itself.
Possibly the most inhospitable of planets in our solar system, Venus is the victim of a runaway greenhouse effect. Our neighboring world is a virtual oven… with a rocky surface baked by 800ºF temperatures and crushed beneath the weight of its own incredibly dense atmosphere, standing “sea level” on Venus would be like being 3,300 feet underwater, just in terms of pressure per square inch. And as if the heat and pressure weren’t enough, Venus’ skies are full of clouds made of corrosive sulphuric acid, lit by bolts of lightning and and whipped along by hurricane-force planetwide winds. All Earth-based probes that have ever landed there only lasted moments on the surface before succumbing to Venus’ destructive environment.
Venus is, quite literally, hellish.
Venus' south polar vortex imaged in infrared. A darker region corresponds to higher temperature and thus lower altitude. Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA.
Unlike Earth, Venus does not have much of an axial tilt. This means there’s little, if any, seasonal variation on Venus. (Actually it does have a tilt… Venus is rotated almost completely upside-down relative to its poles, and so in effect still has very little axial tilt.) And since its cloud cover is so dense and it lacks a hydrologic cycle to move heat energy around, it pretty much stays at a constant level of “extreme broil” all across Venus’ surface.
Surface weather on Venus, although unpleasant, is consistent.
Yet based on an international team’s new research this is not the case higher up in Venus’ atmosphere. A new look at old data has uncovered changing weather patterns visible in infrared light at about 68 miles (110 kilometers) above the planet’s surface in the cold, clear air above the acid clouds.
“Any variability in the weather on Venus is noteworthy, because the planet has so many features to keep atmospheric conditions the same,” said Dr. Tim Livengood, a researcher with the National Center for Earth and Space Science Education and the University of Maryland, now stationed at NASA’s Goddard Space Flight Center in Greenbelt.
Dr. Theodor Kostiuk of NASA Goddard explains further: “Although the air over the polar regions in these upper atmospheric layers on Venus was colder than the air over the equator in most measurements, occasionally it appeared to be warmer. In Earth’s atmosphere, a circulation pattern called a ‘Hadley cell’ occurs when warm air rises over the equator and flows toward the poles, where it cools and sinks. Since the atmosphere is denser closer to the surface, the descending air gets compressed and warms the upper atmosphere over Earth’s poles. We saw the opposite on Venus.”
Many factors could be contributing to Venus’ upper-atmospheric variabilities, such as interactions between opposing winds blowing around the planet at over 200 mph, giant vortexes that churn around its poles, and possibly even solar activity, like solar storms and coronal mass ejections which may create turbulence in Venus’ upper atmosphere.
“The mesosphere and thermosphere of Venus are dynamically active. Wind patterns resulting from solar heating and east to west zonal winds compete, possibly resulting in altered local temperatures and their variability over time.”
– Lead author Dr. Guido Sonnabend, University of Cologne, Germany
Artist concept of Venus' surface. (NASA)
The team also found that the temperatures of Venus’ atmosphere change over time, spanning weeks, months, years… even decades. Temperatures measured in 1990-91 are warmer than in 2009, and equatorial temperatures were even warmer in 2007.
“In addition to all these changes, we saw warmer temperatures than those predicted for this altitude by the leading accepted model,” said Kostiuk. “This tells us that we have lots of work to do updating our upper atmospheric circulation model for Venus.”
Even though Venus is compositionally similar to Earth and has a similar size as well, at some point in its history it lost all of its water to space and became the cloud-covered oven it is today. Studying Venus will help scientists learn how this may have happened and – hopefully! – learn how to prevent the same fate from ever befalling Earth.
The paper, led by Dr. Guido Sonnabend of the University of Cologne, Germany and co-authored by Drs. Livengood and Kostiuk, appeared July 23 in the online edition of the journal Icarus.
A cluster of galaxies as seen from the Hubble Space Telescope
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Hey. We’re all aware of Einstein’s theories and how gravity affects light. We know it was proved during a total solar eclipse, but what we’ve never realized in observational astronomy is that light just might get bent by other gravitational influences. If it can happen from something as small as a star, then what might occur if you had a huge group of stars? Like a galaxy… Or a group of galaxies!
What’s new in the world of light? Astrophysicists at the Dark Cosmology Centre at the Niels Bohr Institute have now gone around the bend and came up with a method of measuring how outgoing light is affected by the gravity of galaxy clusters. Not only does each individual star and each individual galaxy possess its own gravity, but a galaxy group is held together by gravitational attraction as well. Sure, it stands to reason that gravity is affecting what we see – but there’s even more to it. Redshift…
“It is really wonderful. We live in an era with the technological ability to actually measure such phenomena as cosmological gravitational redshift”, says astrophysicist Radek Wojtak, Dark Cosmology Centre under the Niels Bohr Institute at the University of Copenhagen.
Together with team members Steen Hansen and Jens Hjorth, Wojtak has been collecting light data and measurements from 8,000 galaxy clusters. Their studies have included calculations from mid-placed members to calibrations on those that reside at the periphery.
“We could measure small differences in the redshift of the galaxies and see that the light from galaxies in the middle of a cluster had to ‘crawl’ out through the gravitational field, while it was easier for the light from the outlying galaxies to emerge”, explains Radek Wojtak.
Until now, the gravitational redshift has only been tested with experiments and observations in relation to distances her on Earth and in relation to the solar system. With the new research the theory has been tested on a cosmological scale for the first time by analyzing galaxies in galaxy clusters in the distant universe. It is a grotesquely large scale, which is a factor 1,022 times greater (ten thousand billion billion times larger than the laboratory test). The observed data confirms Einstein’s general theory of relativity. Credit: Dark Cosmology Centre, Niels Bohr Institute
The next step in the equation is to measure the entire galaxy cluster’s total mass to arrive at its gravitational potential. Then, using the general theory of relativity, the gravitational redshift could be determined by galaxy location.
“It turned out that the theoretical calculations of the gravitational redshift based on the general theory of relativity was in complete agreement with the astronomical observations.” explains Wojtak. “Our analysis of observations of galaxy clusters show that the redshift of the light is proportionally offset in relation to the gravitational influence from the galaxy cluster’s gravity. In that way our observations confirm the theory of relativity.”
Of course, this kind of revelation also has other implications… theoretical dark matter just might play a role in gravitational redshift, too. And don’t forget dark energy. All these hypothetical models need to be taken into account. But, for now, we’re looking at the big picture in a different way.
“Now the general theory of relativity has been tested on a cosmological scale and this confirms that the general theory of relativity works and that means that there is a strong indication for the presence of dark energy”, explains Radek Wojtak.
As Walt Whitman once said, “I open the scuttle at night and see the far-sprinkled systems, And all I see multiplied as high as I can cypher edge but the rim of the farther systems. Wider and wider they spread, expanding, always expanding,Outward and outward and forever outward.”
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address to join in.
