Space Addicts

A superluminous supernova may sound like a designation dreamed up by someone with a penchant for hyperbole, but such explosions are deserving of the extravagant language. They are very big blasts—and two newfound examples originated in the very distant past.

Astronomers using two telescopes atop Mauna Kea in Hawaii have discovered a pair of supernovae that occurred more than 10 billion years ago, when the universe was less than a quarter of its present age. The older, and hence more remote, of the two supernovae ranks as the most distant such event known.

The researchers were able to spot the ancient stellar explosions, whose light has only just reached Earth, because of the extreme luminosity of the supernovae—the newly discovered blasts may signal the cataclysmic death of giant stars more than 100 times as massive as the sun. Although such superluminous explosions have been detected in the relatively nearby universe, they ought to be more common in the early universe, when massive stars were more numerous.

Jeff Cooke of the Swinburne University of Technology in Australia and his colleagues reported the discoveries in a study published online October 31 in Nature. (Scientific American is part of Nature Publishing Group.) The supernovae pair, which have been designated SN 2213-1745 and SN 1000+0216, were identified from deep-sky images taken at the 3.6-meter Canada—France-–Hawaii Telescope between 2003 and 2008. The researchers then used the 10-meter Keck I telescope to make spectral measurements of the galaxies where the supernovae were discovered, which revealed precise distance measurements for both host galaxies.

Cosmologists and astrophysicists gauge cosmic distance using redshift, a measure of how much light has been stretched toward longer wavelengths as it propagates across an expanding universe. SN 2213-1745 lies at a redshift of 2.05, which implies that the supernova’s progenitor star exploded 10.4 billion years ago. (The universe is now about 13.7 billion years old.) The extreme brightness and slow fading of SN 2213-1745 match up well with the properties expected of a so-called pair-instability supernova, the death of a giant star brought on by energetic gamma rays giving off pairs of matter and antimatter particles. The star that exploded as SN 2213-1745 may have been as massive as 250 suns, the researchers estimate.

Did you know that Aurora are not unique to Earth? Many other planets generate a significant magnetic field - Mercury, Earth, Jupiter, Saturn, Uranus and Neptune. Venus does not.

Aurora on Saturn...

Aurora on Jupiter...

Aurora on Jupiter's moon Io...

This image was taken by Galileo from a distance of 1.3m km. The blue light is caused by volcanic plumes.

Nasa's Fermi Gamma-ray Space Telescope has been used to measure the amount of starlight that has shone in the Universe.

The starlight continues to exist even when the stars themselves have ceased to shine. It's referred to as extragalactic background light (EBL) and functions as a kind of stellar fog, and has a measurable effect on the data gathered by the Fermi telescope.

Fermi detects gamma rays from distant sources such as blazars -- galaxies powered by black holes that emit high-energy gamma rays -- and, by observing the energy of gamma rays emitted by nearby blazars compared to those at far greater distances, has been able to determine the strength of the EBL.

The EBL dampens the blazar radiation as it travels through space because occasional collisions between starlight and gamma ray photons cause those photons to be converted into an electron and a positron and are thus lost to the Fermi telescope's sensor. The most distant blazars were observed to be missing the majority of their high-energy gamma rays.

Using these measurements the team, led by Marco Ajello of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University, were able to deduce the average stellar density of the Universe -- 1.4 stars per 100 billion cubic light years -- as well as the average distance between those stars (around 4,150 light years).

The results form part of Fermi's ongoing mission to discover more about the Universe through analysis of its gamma rays.

Framework offers starting point to explaining how particles cope with fluctuations in gravity.

Could an analysis based on relatively simple calculations point the way to reconciling the two most successful — and stubbornly distinct — branches of modern theoretical physics? Frank Wilczek and his collaborators hope so.

The task of aligning quantum mechanics, which deals with the behaviour of fundamental particles, with Einstein’s general theory of relativity, which describes gravity in terms of curved space-time, has proved an enormous challenge. One of the difficulties is that neither is adequate to describe what happens to particles when the space-time they occupy undergoes drastic changes — such as those thought to occur at the birth of a black hole. But in a paper posted to the arXiv preprint server on 15 October (A. D. Shapere et al. http://arxiv.org/abs/1210.3545; 2012), three theoretical physicists present a straightforward way for quantum particles to move smoothly from one kind of ‘topological space’ to a very different one.

The analysis does not model gravity explicitly, and so is not an attempt to formulate a theory of ‘quantum gravity’ that brings general relativity and quantum mechanics under one umbrella. Instead, the authors, including Nobel laureate Frank Wilczek of the Massachusetts Institute of Technology (MIT) in Cambridge, suggest that their work might provide a simplified framework for understanding the effects of gravity on quantum particles, as well as describing other situations in which the spaces that quantum particles move in can radically alter, such as in condensed-matter-physics experiments. “I’m pretty excited,” says Wilczek, “We have to see how far we can push it.”

The idea is attracting attention not only because of the scope of its possible applications, but because it is based on undergraduate-level mathematics. “Their paper starts with the most elementary framework,” says Brian Greene, a string theorist at Columbia University in New York. “It’s inspiring how far they can go with no fancy machinery.”

Wilczek and his co-authors set up a hypothetical system with a single quantum particle moving along a wire that abruptly splits into two. The stripped-down scenario is effectively the one-dimensional version of an encounter with ripped space-time, which occurs when the topology of a space changes radically. The theorists concentrate on what happens at the endpoints of the wire — setting the ‘boundary conditions’ for the before and after states of the quantum wave associated with the particle. They then show that the wave can evolve continuously without facing any disruptions as the boundary conditions shift from one geometry to the other, incompatible one. “You can smoothly follow this process,” says Al Shapere at the University of Kentucky in Lexington, a co-author on the paper, adding that, like a magician’s rings, the transformation is impossible to visualize, but does make mathematical sense.

The desire to escape the mathematical headaches caused by such transformations is one motivation for string theory, which allows smooth changes in the topology of space-time, says Greene. He suggests that the approach developed by Wilczek, Shapere and MIT undergraduate student Zhaoxi Xiong could be applied within string theory too.

Although Wilczek originally believed that the result was new, a 1995 paper by Aiyalam Balachandran of Syracuse University in New York proposed a similar strategy for describing changes in topology in quantum mechanics (A. P. Balachandran et al. Nucl. Phys. B 446, 299–314; 1995). Balachandran acknowledges that his work hasn’t hit the mainstream and says that he hopes Wilczek’s paper will prompt others to take a closer look. “Conventional approaches to this problem don’t get very far,” he says. “This opens up a new technique.”

The framework might also provide inspiration for experimentalists working on condensed matter. Rob Myers, a string theorist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada, says that he expects it to be relevant to an area called quantum quenches, in which quantum systems evolve in isolation from the environment and are then kicked out of equilibrium by an action of the experimentalist. Condensed-matter physicists have developed several quantum systems — including cold-atom traps and superconducting circuits — that can be used to test this idea.

The first “Alien” movie was promoted with the celebrated tagline, “In space, no one can hear you scream.” But a group of students want to find out if this is really true, and they’re asking the public for help. Students from the University of Cambridge in the UK will be loading human screams onto a smartphone that will be launched into space in December 2012 on a nanosatellite. The screams will be played at maximum volume while the smartphone is in low Earth orbit, and at the same time as the phone will record the playback to test if it’s possible to capture the sound of screaming in space. They want the best screams possible, and so are inviting the public to submit their screams via video. There will also be public voting on the screams to determine which screams will go to space.

You know you’ve always wanted to do this….. “Obviously, we’re not expecting to get much back, there may be some buzzing, but this is more about getting young people interested in satellites and acoustics, perhaps encouraging them to consider future study in science or engineering” said Edward Cunningham, a physics undergraduate at Churchill College and one of the members of the Cambridge University Space Flight group (CUSF).

What is actually being tested is verifying the capabilities of a smartphone to control a satellite in space. UK space company Surrey Satellite Technology and their STRaND (Surrey Training Research and Nanosatellite Demonstration) team ran a Facebook competition to find apps to go into orbit – and CUSF’s screaming app was one of the winners. STRaND-1 project is touted as the “World’s first SmartPhone Nanosatellite.”

The phone will run on Android’s open-source operating system, and a computer, built at the Surrey Space Centre, will test the vital statistics of the phone once in space. When all the tests are complete, the plan is to switch off the micro-computer and the smartphone will be used to operate parts of the satellite. At its lowest, the phone will orbit 400km above the Earth, roughly the same as the International Space Station.

“Modern smartphones are pretty amazing,” said Shaun Kenyon, the project manager at Surrey Satellite Technology. “We want to see if the phone works up there, and if it does, we want to see if the phone can control a satellite.”

To submit your scream, create a YouTube video and send it in at www.screaminspace.com. Each video must be at most ten seconds long, and there will be ten winning screams which can be voted for by the public on the project’s website. Screams must be entered before midnight (UTC) on Sunday November 4, 2012. The winning videos will be announced later and loaded onto the phone for launch, which is scheduled before the end of this year.

A giant wave of super-hot solar plasma larger than the Earth erupted from the sun on Friday (Oct. 19) in a spectacular display captured by a NASA spacecraft.

The huge solar prominence occurred at 4:15 a.m. EDT (0815 GMT) and was recorded in amazing detail by the high-definition cameras aboard NASA's Solar Dynamics Observatory before escaping the sun.

"Once it started breaking away, the process only took 10 hours before it was out of sight," NASA media specialist Steele Hill explained in a photo description. "The prominence stretched out many times the size of Earth."

The Solar Dynamics Observatory showed the solar prominence as a wispy red-orange wave stretching out from the lower right section of the sun. The image was recorded in the 304 Angstrom wavelength of extreme ultraviolet light, according to Hill.

Prominences are eruptions of charged solar plasma that appear to arc out away from the sun's edge, or limb, in spacecraft and telescope views. The structures are shaped by extreme magnetic field. Some loop-like prominences are short-lived, lasting only a few minutes. Others can be more stable, lasting hours or days, NASA scientists have said in the past.  

NASA's Solar Dynamics Observatory is one of several spacecraft keeping a constant watch on the sun to track major solar flares, eruptions other space weather events. The sun is currently in an active phase of its 11-year solar weather cycle and is expected to reach its peak activity in 2013.

We are a step closer to understanding how supermassive black holes behave after a photo of the phenomena shows that they blast a jet of material similar to a fighter jet's afterburner exhaust.

Curtin University researcher Leith Godfrey said the jets of material needed to be understood if scientists were to understand how galaxies formed and grew.

A photo published in the Astrophysical Journal Letters over the weekend showed the galaxy-scale jet had bright and dark regions, similar to the phenomenon in an afterburner exhaust called 'shock diamonds' whereby the differing pressure of gas hitting ambient air pressure creates disc-like shapes.

"One intriguing possibility is that the pattern we see in this cosmic jet is produced in the same way as the pattern in the exhaust from fighter jet engines," Dr Godfrey said in a statement on Monday.

The jets were produced when material fell on to a supermassive black hole at the centre of a galaxy, he said. Details beyond that were unknown.

"Massive jets like this one have been studied for decades, since the beginning of radio astronomy, but we still don't understand exactly how they are produced or what they're made of," he said.

"If the brighter patches are caused by the same process in astronomical jets as they are in earthly jet engines, then the distance between them can give us important information about the power of the jet and the density of the surrounding space."

The jets were extremely powerful and were believed to stop stars forming in their parent galaxy, limiting how big the galaxies could grow and effecting how the universe looked today, he said.

A study of hundreds of galaxies has revealed an unexpected pattern of change that goes back more then half the age of the universe. Astronomers had thought that disk galaxies in the nearby universe had settled into their present form about 8 billion years ago, with little change since. However observations by the Hubble Space Telescope and the Keck telescopes in Hawaii have shown the opposite to be true. 

According to NASA's Goddard Space Flight Center astronomer Dr Susan Kassin "the trend we've observed instead shows the opposite, that galaxies were steadily changing over this time period".

Prior to this research, previous studies had removed galaxies that did not look like the well-ordered rotating disks now common in the universe today. Co-author on the paper of the findings Dr Benjamin Weiner, from University of Arizona said "By neglecting them, these studies examined only those rare galaxies in the distant universe that are well-behaved and concluded that galaxies didn't change." 

Rotation in galaxies such as our own Milky Way or the Andromeda Galaxy dominates over other internal motion, so they take the form of ordinary disk-shaped systems. Whereas the most distant blue galaxies - their colour indicates stars are forming within them - are very different, they are instead disorganised with motion in multiple directions. 

The trend we've observed instead shows the opposite, that galaxies were steadily changing over this time period

Dr Susan Kassin, Goddard Space Flight Centre

However these blue galaxies show more organised motion and faster rotation speeds the closer they are observed to the present. This means that they are gradually settling into well behaved disk shapes. The trend appears to be true for galaxies of all masses, however the most massive systems show the highest level of organisation.

The researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like the Milky Way.

Those involved in the study looked at all galaxies with emission lines bright enough to be able to determine internal motions. Emission lines are the discrete wavelengths of radiation emitted by the gas within a galaxy. They are revealed when a galaxy's light is separated into its component colours and carry information about internal motions and distance.

It's believed that the Milky Way galaxy would have gone through the same evolution as the galaxies in the sample, before it gradually settled into its present state at the time the sun and solar system were being formed.

Astronomers have found the nearest planet outside our Solar System, circling one of the stars of Alpha Centauri, four light-years away.

The planet has at minimum the same mass as Earth, but circles its star far closer than Mercury orbits our Sun.

It is therefore outside the "habitable zone" denoting the possibility of life, as the researchers report in Nature.

However, studies on exoplanets increasingly show that a star with one planet is likely to have several.

At the very least, the work answers the question first posed in ancient times about planets around our nearest stellar neighbours.

The closest star to the Sun is Proxima Centauri, which is believed to be part of a three-star system that includes the brighter stars Alpha Centauri A and B.

The planet was found near Alpha Centauri B by the Harps instrument at the European Southern Observatory's La Silla facility in Chile.

That puts it far closer to Earth than any of the more than 840 confirmed exoplanets

Like a dance between one enormous and one tiny partner, as an exoplanet orbits its much larger host star, its gravity causes the star to move in a small orbit.

What is redshift?

The term "redshift" arises from the fact that light from more distant objects shows up on Earth more red than when it left its source

The colour shift comes about because of the Doppler effect, which acts to "stretch" or "compress" waves from moving objects

It is at work in the sound of a moving siren: an approaching siren sounds higher-pitched and a receding one sounds lower-pitched

In the case of light, approaching objects appear more blue and receding objects appear more red

The expansion of the Universe is accelerating, so in general, more distant objects are moving away from us (and each other, and everything else) more quickly than nearer ones

At cosmic distances, the shift can profoundly affect the colour - the factor by which the wavelength is "stretched" is called the redshift

Harps and instruments like it measure the subtle change in colour - the redshift or blueshift - of the host star's light as its orbit moves it slightly closer to and further away from Earth.

The planet whips around Alpha Centauri B in just 3.6 days, and is estimated to have a surface temperature of about 1,200C.

Many planets in similar orbits are "tidally locked", meaning the same side is always facing the host star, but further observations will be required to find out if that is the case

Since the very first planets outside our solar system were discovered in the early 1990s, the hope has been to find an "Earth twin" - a planet like ours, orbiting a star like ours, at a distance like ours.

The new planet around Alpha Centauri B matches Earth only in terms of its mass - making it among the smallest exoplanets we know of.

But in a catalogue with hundreds of confirmed planets and thousands of planet candidates added since 1992, it is otherwise unremarkable - except for its proximity.

"Alpha Centauri B is of course a very special case - it's our next door neighbour," said Stephane Udry of the Observatory in Geneva and senior author of the paper.

"So even if the discovery just stands perfectly normally in the discoveries we have had up to now, it's a landmark discovery, because it's very low-mass and it's our closest neighbour."

Astronomers have found a planet whose skies are illuminated by four different suns - the first known of its type.

The distant world orbits one pair of stars and has a second stellar pair revolving around it.

It remains a mystery how the Neptune-like world avoids being pulled apart by the gravitational forces generated its four stars.

The find was made by volunteers using the Planethunters.org website along with a team from UK and US institutes.

A scientific paper outlining the quadruple star system has been posted on the Arxiv pre-print server.

The planet, located just under 5,000 light-years away, has been named PH1 after the Planet Hunters site.

It is thought to be a "gas giant" slightly larger than Neptune but over six times the size of the Earth.

"You don't have to go back too far before you would have got really good odds against one of these systems existing," Dr Chris Lintott, from the University of Oxford, told BBC News.

"All four stars pulling on it creates a very complicated environment. Yet there it sits in an apparently stable orbit.

"That's really confusing, which is one of the things which makes this discovery so fun. It's absolutely not what we would have expected."

Binary stars - systems with pairs of stars - are not uncommon. But only a handful of the planets have been found to orbit such binaries. And none of these are known to have another pair of stars circling them.

Kepler Space Telescope

Stares fixedly at a patch corresponding to 1/400th of the sky

Looks at more than 155,000 stars

Has so far found 2,321 candidate planets

Among them are 207 Earth-sized planets, 10 of which are in the "habitable zone" where liquid water can exist

On how the planet survives without being pulled apart, Dr Lintott said: "There are six other well-established planets around double stars, and they're all pretty close to those stars. So I think what this is telling us is planets can form in the inner parts of protoplanetary discs (the torus of dense gas that gives rise to planetary systems).

"The planets are forming close in and able to cling to a stable orbit there. That probably has implications for how planets form elsewhere."

PH1 was discovered by two US volunteers using the Planethunters.org website: Kian Jek of San Francisco and Robert Gagliano from Cottonwood, Arizona.

They spotted faint dips in light caused by the planet passing in front of its parent stars. The team of professional astronomers then confirmed the discovery using the Keck telescopes on Mauna Kea, Hawaii.

Founded in 2010, Planethunters.org aims to harness human pattern recognition to identify transits in publicly available data gathered by Nasa's Kepler Space Telescope.

Kepler was launched in March 2009 to search for Earth-like planets orbiting other stars.

Visitors to the Planet Hunters website have access to randomly selected data from one of Kepler's target stars.

Europe's rival to GPS is stepping up its efforts to provide precise navigation, road transport management, search and rescue services and secure banking.

Galileo already combines the most precise atomic clock ever flown for navigation -- accurate to 1 second in 3 million years -- with a powerful transmitter to broadcast navigation data worldwide.

It launched two more satellites into space on Friday from a South American spaceport in French Guiana.

The satellites, named David and Sif1, join another pair that has been orbiting the Earth since last year. Now that the four satellites form a mini-constellation, Galileo can be validated and fine-tuned, after which 14 more satellites will be deployed by the end of 2014.

The two satellites just launched are the first to carry search and rescue antennas part of the international Cospas-Sarsat system, which detects and locates emergency beacons activated by aircraft, ships and backcountry hikers in distress.

Galileo aims to provide a highly accurate, guaranteed global positioning service that’s better than GPS and controlled by civilians. Galileo will be compatible with GPS, which is maintained by the U.S. government, as well as the Russian government’s GLONASS. GPS and GLONASS aren’t Galileo’s only competitors -- China’s Beidou constellation is already operating, as well.

According to ZDNet, Galileo “services include a freely available open service, for use in in-car navigation systems, for example; a public regulated service, for first responders such as police and ambulance; a search and rescue service, for maritime emergencies, among others; a safety of life service, for aviation; and a fee-based commercial service, for mapping and surveying providers, for example.”

Galileo, which should be certified and ready to use in 2015, is a joint initiative of the European Commission and the European Space Agency, and one of the largest space projects ever conducted in Europe.

One of the bravest things that was ever done with the Hubble Space Telescope was to find a patch of sky with absolutely nothing in it—no bright stars, no nebulae, and no known galaxies—and observe it. Not just for a few minutes, or an hour, or even for a day. But orbit-after-orbit, for a huge amount of time, staring off into the nothingness of empty space, recording image after image of pure darkness.

What would we find, out beyond the limits of what we could see? Something? Nothing? After a total of more than 11 days of observing this tiny area of the sky, this is what we found:

The Hubble Ultra Deep Field—the deepest view ever of the Universe, was the result. With all those orbits spent observing what appears to be a blank patch of sky, what we were really doing was probing the far-distant Universe, seeing beyond what any human eye—even one aided by a telescope—could ever hope to see. It took literally hundreds of thousands of seconds of observations across four separate color filters to produce these results.

What you’re seeing—in practically every point or smear of light—is an individual galaxy. The result gave us the information that a very large number of galaxies exist in a minuscule region of the sky: around 10,000 in the tiny volume surveyed by the Hubble Ultra Deep Field image, below.

By extrapolating these results over the entire sky (which is some 10 million times larger), we were able to figure out—at minimum—that there were at least 100 billion galaxies in the entire Universe. I even made a video about it.

But that’s not the end of the story; not by a long shot. You see, there might be at least 100 billion galaxies, based on what we’ve observed, but there might be more. Galaxies that are too dim to observe with “only” 11 days of Hubble data. Galaxies that are redshifted too far for even Hubble’s farthest infrared filter to pick up. Galaxies that might appear, if only we had the patience to look for longer.

So that’s exactly what we did, looking for a total of 23 days over the last decade—more than twice as long as the Ultra-Deep Field—in an even smaller region of space. (There are over 1,000 observing proposals submitted to Hubble every cycle, so getting that much time, even spread over a decade, is remarkable.) Ladies and Gentlemen, may I present to you the Hubble Extreme Deep Field!

This picture may look familiar to you, even though you’ve probably never seen it before. The Extreme Deep Field (or XDF) is actually a part of the Ultra Deep Field, which you can see for yourself if you rescale both images and rotate them at 4.7 degrees relative to one another, as I did here.

The XDF has far more galaxies in it than the HUDF does in a comparable region of space. Take a look for yourself at a small portion of these images, compared side-by-side with one another, and you can clearly see how many more galaxies there are in the XDF with your own eyes.

Sure, the Ultra-Deep one (at left) is very impressive, especially considering that—by all appearances—this is just a blank patch of featureless sky. But there are maybe 75% more galaxies-per-patch-of-sky in the XDF! Applying the XDF results to the entire sky, we find that there are more like 176 billion galaxies in the entire Universe, a huge increase from our previous estimate from the HUDF.

How do we estimate that there are so many? For starters, the area of the XDF is just a tiny, tiny fraction of the full Moon.

If you assume that the XDF is a typical region of outer space, you can calculate how many XDFs it would take to fill the entire night sky; it’s about 32 million. Multiply by the number of galaxies you find in the XDF—which is around 5,500—and that’s how we arrive at 176 billion galaxies, at least, in the Universe.

But there’s more to the story than that.

We’re taking a region of space that has very few nearby galaxies, or galaxies whose light takes less than a few billion years to reach us. We’ve selected a deliberately low-density portion of the nearby Universe. The XDF has found many more galaxies whose light has traveled between 5 and 9 billion years to reach us, which are relatively dim galaxies that the HUDF simply couldn’t pick up. But where it really shines is in the early Universe, at finding galaxies whose light has been on its was for more than 9 billion years, finding the majority of new galaxies there.

But even the XDF is not optimized for finding these galaxies; we’d need an infrared space telescope for that, which is what James Webb is going to be. When that comes around, I wouldn’t be surprised to find that there are maybe even close to a trillion galaxies in the observable Universe; we just don’t have the tools to find them all yet. In the meantime, our best tool—the Hubble Space Telescope—is showing us that the deeper we look, the more we’ll continue to be rewarded with new, faint, and distant galaxies, as well as richer details in the already discovered ones.

It makes me so impatient for a more powerful telescope with the ability to see far into the infrared, because I can’t help but wonder what’s still invisible to even the XDF. Twice as many galaxies? Four times? Fainter ones, redder ones, more distant ones, or all of them? There’s at least 176 billion of them in our Universe, but I can’t help wonder, “how many more?”

Astronomers using NASA’s Spitzer Space Telescope have announced one of the most precise measurements yet of the Hubble constant, or the rate at which our universe is stretching apart.

The Hubble constant is named after the astronomer Edwin P. Hubble, who astonished the world in the 1920s by confirming our universe has been expanding since it exploded into being 13.7 billion years ago. In the late 1990s, astronomers discovered the expansion is accelerating, or speeding up, over time. Determining the expansion rate is critical for understanding the age and size of the universe.

Astronomers using NASA’s Spitzer Space Telescope have greatly improved the cosmic distance ladder used to measure the expansion rate of the universe, as well as its size and age. The cosmic distance ladder, symbolically shown here in this artist’s concept, is a series of stars and other objects within galaxies that have known distances.

Unlike NASA’s Hubble Space Telescope that views the cosmos in visible and short-wavelength infrared light, Spitzer took advantage of long-wavelength infrared light for its latest Hubble constant measurement of 74.3 kilometers per second per megaparsec. A megaparsec is roughly three million light-years.

This finding agrees with an independent supernovae study conducted last year by researchers primarily based at the Space Telescope Science Institute in Baltimore, MD, and improves by a factor of three on a seminal 2001 Hubble Space Telescope study using a similar technique as the current study.

“Spitzer is yet again doing science beyond what it was designed to do,” said project scientist Michael Werner at NASA’s Jet Propulsion Laboratory in Pasadena, CA. Werner has worked on the mission since its early concept phase more than 30 years ago. “First, Spitzer surprised us with its pioneering ability to study exoplanet atmospheres,” said Werner, “and now, in the mission’s later years, it has become a valuable cosmology tool.”

In addition, the findings were combined with published data from NASA’s Wilkinson Microwave Anisotropy Probe to obtain an independent measurement of dark energy, one of the greatest mysteries of our cosmos. Dark energy is thought to be winning a battle against gravity, pulling the fabric of the universe apart. Research based on this acceleration garnered researchers the 2011 Nobel Prize in physics.

“This is a huge puzzle,” said the lead author of the new study, Wendy Freedman of the Observatories of the Carnegie Institution for Science in Pasadena. “It’s exciting that we were able to use Spitzer to tackle fundamental problems in cosmology: the precise rate at which the universe is expanding at the current time, as well as measuring the amount of dark energy in the universe from another angle.” Freedman led the groundbreaking Hubble Space Telescope study that earlier had measured the Hubble constant.

Glenn Wahlgren, Spitzer program scientist at NASA Headquarters in Washington, D.C. said infrared vision, which sees through dust to provide better views of variable stars called cepheids, enabled Spitzer to improve on past measurements of the Hubble constant using Cepheids.

“These pulsating stars are vital rungs in what astronomers call the cosmic distance ladder: a set of objects with known distances that, when combined with the speeds at which the objects are moving away from us, reveal the expansion rate of the universe,” said Wahlgren.

Cepheids are crucial to the calculations because their distances from Earth can be measured readily. In 1908, Henrietta Leavitt discovered these stars pulse at a rate directly related to their intrinsic brightness.

To visualize why this is important, imagine someone walking away from you while carrying a candle. The farther the candle traveled, the more it would dim. Its apparent brightness would reveal the distance. The same principle applies to cepheids, standard candles in our cosmos. By measuring how bright they appear on the sky, and comparing this to their known brightness as if they were close up, astronomers can calculate their distance from Earth.

This graph illustrates the Cepheid period-luminosity relationship, which scientists use to calculate the size, age and expansion rate of the universe. The data shown are from NASA’s Spitzer Space Telescope, which has made one of the most precise measurements yet of the universe’s expansion rate by recalculating the distance to pulsating stars called Cepheids. (Image credit: NASA/JPL-Caltech/Carnegie)

Spitzer observed 10 cepheids in our own Milky Way galaxy and 80 in a nearby neighboring galaxy called the Large Magellanic Cloud. Without the cosmic dust blocking their view, the Spitzer research team was able to obtain more precise measurements of the stars’ apparent brightness, and thus their distances. These data opened the way for a new and improved estimate of our universe’s expansion rate.

“Just over a decade ago, using the words ‘precision’ and ‘cosmology’ in the same sentence was not possible, and the size and age of the universe was not known to better than a factor of two,” said Freedman. “Now we are talking about accuracies of a few percent. It is quite extraordinary.”