Posted on by Nancy Atkinson

Did Earth Have More Than One Moon?

Scientists looking at the various Lagrangian Points in our solar system noticed a pattern. Lagrange points, (named after their discoverer Josef Lagrange) are five special locations in the vicinity of two orbiting masses where a third, smaller mass can orbit at a fixed distance from the larger masses. Essentially, the gravity from each large mass is equal at that point and the smaller object can be “trapped” there. The 4th and 5th Largrange points, called L4 and L5, are stable points. Researchers Jack Lissauera, and John Chambers noticed that more than 2200 cataloged asteroids are located about the L4 and L5 points of the Sun–Jupiter system, and five bodies have been discovered around the L4 point of the Sun–Neptune system. Small satellites have also been found librating about the L4 and L5 points of two of Saturn’s moons. However, no objects have been discovered around the Earth–Moon L4 and L5 points. Their research led them to believe that other small moons may once have existed in these points.

The triangular Lagrange points, L4 and L5, form equilateral triangles with the two massive bodies (here, the Earth and the moon) and objects near L4 and L5 can remain close to these locations indefinitely.

Lissauera and Chambers say that using numerical integrations, they’ve shown that orbits near the Earth–Moon L4 and L5 points can survive for over a billion years even when the sun’s gravity is thrown into the mix. However, when the small perturbations from the other planets are present, that can destabilize the orbits at L4 and L5 within several million years. So, they deduced that even though there’s no objects at those points right now, that doesn’t mean there wasn’t something there in the past.

The leading candidate for the theory of the moon’s formation is that a Mars-sized object hit the Earth and the resulting debris formed the moon. The two researchers say other debris would have been present as well, and may have been trapped at the L4 and L5 points.

However, one has to wonder, with the moon, as well as Earth, in a state of flux following the collision, their gravitational fields may have been unstable enough to preclude any L points at the stage where the other debris or moons were in the area. Also, the moon used to be closer to Earth, and the L points would have changed over time, and this change also might have been enough to disengage any “trapped” moons.

But it’s interesting to consider the night sky with multiple moons.

Original News Sources: Icarus, New Scientist

Posted on by Fraser Cain

Finally, Some Help

As you’ve probably noticed, Universe Today has gotten in influx of talented writers to pitch in around here. Tammy Plotner, of course, has been working with me for years, and so have Nancy Atkinson and Mark Mortimer. Ian O’Neill and Nick Wethington are newer contributors, but have definitely proven to be great additions to the team. Thanks to them, I’ve been able to tail back my writing a little to be able to catch up on the world’s longest to-do list.

One huge piece of news, though. As of yesterday, Nancy is now working full time for Universe Today, and will be able to contribute many more stories over the coming weeks and months (dare I say… decades?). Nancy is going to be joining the Astronomy Cast Live team at the upcoming 212th American Astronomical Society meeting in St. Louis from June 1-June 5, 2008, where we’ll try to provide an absurd amount of coverage.

I hope you’ve all noticed and appreciated the jump in quality and coverage from Universe Today, and I’m hoping things will just get better from here.

Fraser Cain
Publisher, Universe Today

Posted on by Fraser Cain

How to Detect Watery Worlds Around Other Stars

The Blue Marble. Image credit: NASA

If you want to know what a watery world might look like orbiting another star, just observe our own planet… from afar. The Blue Marble image of Earth, taken by the Apollo 17 astronauts on December 1972, shows how our planet is 70% water. Another world like ours, orbiting a distant star should be obvious – assuming you have a much more powerful telescope, and use the right techniques to analyze the light bouncing off the watery world.

Researchers from Penn State and the University of Hawaii have developed a technique that they think will help identify these watery worlds; potential homes for life around other stars. This technique is detailed in the most recent edition of the journal Icarus.

“We are looking for Earth-like planets in the habitable zone of their star, a band not too hot nor too cold for life to exist,” says Darren M. Williams, associate professor of physics and astronomy, Penn State Erie. “We also want to know if there is water on these planets.”

Here’s how you might tell the difference between a hellish planet like Venus, and a more comfortable watery world like Earth. A planet like Venus has a very dense atmosphere that scatters sunlight in all directions. From our vantage point, we would see the amount of light coming from the planet change depending on its position to its parent star. Just like Venus, we would see this extrasolar planet go through phases, changing in brightness in a very predictable way.

A watery world, like the Earth, would actually appear much darker when the whole disk is illuminated, since water is darker than dirt. But when the planet is in crescent, sunlight would glance off the surface of the water, and it would actually appear brighter.

The astronomers want to monitor the light curve of a distant planet as it spins on its axis and orbits its star. By watching the brightness of the light coming from the planet, they should be able to determine if it has a dense Venusian atmosphere, or is a better match for a watery world.

The equipment isn’t ready yet, but in the next 10 to 20 years, an observatory will probably be built with enough sensitivity to collect light from Earth-sized planets orbiting other stars. And this method should help determine if they’ll watery worlds, capable of supporting life.

Original Source: Penn State News Release

Posted on by Nancy Atkinson

Only 11 Space Shuttle Missions Remain

Space shuttle Discovery now sits majestically out on launch pad 39A, preparing for the upcoming STS-124 mission to the International Space Station. With the shuttle program slated to terminate in 2010, there’s a limited amount of times we’ll see that sight again: a space shuttle will crawl out to the pad only 10 more times –or possibly only 9 more. And whether that thought chokes you up a bit, or evokes a shout of “It’s about time!” here’s a quick look at the remaining shuttle missions and what each will accomplish. All dates and personnel are subject to change. (Updated 7/7/08)


Mission: STS-124
Proposed Launch Date: May 31, 2008, 5:02 pm EDT
Shuttle: Discovery
Mission Description: Discovery will bring the Kibo Japanese Experiment Module – Pressurized Module (JEM-PM) and the Japanese Remote Manipulator System (JEM-RMS) to the ISS. This is the 10th flight since the Columbia disaster, and the first mission that includes all the design modification to the external tank. Crew: Mark Kelly, Ken Ham, Mike Fossum, Karen Nyberg, Ronald Garan and Akihiko Hoshide, as well as bringing Greg Chamitoff to the station as part of Expedition 18.


Mission: STS-125
Proposed Launch Date: ~ October 8, 2008
Shuttle: Atlantis
Mission Description: Atlantis will fly to the Hubble Space Telescope for the fifth and final servicing mission for the venerable telescope, improving the observatory’s capabilities through 2013. Since the shuttle won’t be going to the ISS, which provides a safe haven in the event of an emergency, another shuttle, Endeavour, must be ready to go at the pad. Hence, the delay from the original launch date of August 28, 2008 as an additional new and improved external tank won’t be ready by then.
Crew: Scott Altman, Greg Johnson, Megan McArthur, Michael Good, John Grunsfeld, Michael Massimino and Andrew Feustel.


Mission: STS-126
Proposed Launch Date: ~ November 10, 2008
Shuttle: Endeavour
Mission Description: Endeavour, on ISS flight ULF2, will deliver supplies to the station in a Multi-Purpose Logistics Module, and execute crew exchange for the ISS.
Crew: Chris Ferguson, Eric Boe, Stephen Bowen, Heidemarie Stefanyshyn-Piper, Don Pettit, R. Shane Kimbrough, as well as bringing Sandra Magnus to the station as part of Expedition 18, and returning Greg Chamitoff back home after his stint as part of Exp. 18.

Mission: STS-119
Proposed Launch Date: February 12, 2009
Shuttle: Discovery
Mission Description: Discovery will bring the fourth starboard truss segment to the ISS on assembly flight 15A, as well as the fourth set of solar arrays and batteries. Click here for a video of how the assembly will be accomplished.
Crew: Lee Archambault, Dominic Antonelli, John Phillips, Steven R. Swanson, Joseph Acaba, Richard Arnold (Acaba and Arnold are Educator Astronauts). Additionally, STS-119 will bring JAXA astronaut Koichi Wakata to the station as part of Expedition 18, and bring home astronaut Sandy Magnus.

Mission: STS-127
Proposed Launch Date: May 15, 2009
Shuttle: Endeavour
Mission Description: Endeavour will deliver and install the final component of the Japanese Experiment Module, the Exposed Facility.
Crew: Mark Polansky, Doug Hurley, Christopher Cassidy, Thomas Marshburn, Dave Wolf, Julie Payette, as well as bringing ISS Expedition 19 Flight Engineer Timothy Kopra to the station and returning Koichi Wakata back home.

Mission: STS-128
Proposed Launch Date: July 30, 2009
Shuttle: Atlantis
Mission Description: Atlantis’ primary payload will be the Italian Multi-Purpose Logistics Module Donatello, which will deliver equipment to allow for bringing the station crew from three to six.
Crew: Not yet set, but currently, Nicole Stott is scheduled to be brought to the station as part of the Expedition 19, and Tim Kopra will get a ride home. The additional astronauts for the increased ISS crew size have not yet been named.


Mission: STS-129
Proposed Launch Date: October 15, 2009
Shuttle: Discovery
Mission Description: Discovery will deliver the first two ExPRESS(Expedite the Processing of Experiments to the Space Station) Logistics Carriers, which allows for “outdoor” experiments at the ISS.
Crew: Not yet named, but astronaut Jeff Williams is scheduled to be brought on board as part of Expedition 20, and Nicole Stott brought home.

Mission: STS-130
Proposed Launch Date: December 10, 2009
Shuttle: Endeavour, (possibly its last flight (see below)
Mission Description: Endeavour will bring supplies to the ISS in the Raffaello Multi-Purpose Logistics Module. No crew for the shuttle or station has yet been named.

Mission: STS-131
Proposed Launch Date: February 11, 2010
Shuttle: Atlantis, on its final flight
Mission Description: Atlantis will deliver the Docking Cargo Module and the third and fourth EXPRESS Logistics Carriers to the ISS on Assembly Flight ULF5.

Mission: STS-132
Proposed Launch Date: April 8, 2010
Shuttle: Discovery, its final flight
Mission Description: deliver the Node 3 components to the ISS, which includes advanced life support systems and a Cupola with a robotic workstation. It’s possible that this flight could be the final space shuttle mission if an additional contingency mission is not needed.

Mission: STS-133
Proposed Launch Date: May 31, 2010
Shuttle: Endeavour (for sure the final flight!)
Mission Description: This is a contingency flight to finish any remaining construction or bring up any remaining components, and possibly bring the 5th ExPRESS Logistics Carrier. If needed, this will be the final space shuttle mission.

Posted on by Fraser Cain

Comet Strikes Increase as We Pass Through the Galactic Plane

There are just so many ways the Universe is out to get us. Astronomers have already considered the threat from our Sun’s orbit around the center of the Milky Way. When our Sun rises up out of flat plane of the Milky Way, it appears we might be less protected from intergalactic radiation and cosmic rays. Well, it looks like passing through the middle of the galactic plane might have its own share of risks: an increased number of comets might be hurled towards the Earth because of gravitational interaction with the densest parts of our galaxy.

Researchers at the Cardiff Centre of Astrobiology have built a computer model of the Solar System’s journey around the Milky Way. Instead of making a perfectly flat orbit around the galaxy’s centre, it actually bounces up and down. At times it can rise right up out of the galactic plane – getting 100 light years above – and then dip down below it. They calculated that we pass through the plane every 35 to 40 million years.

And this time period seems to match dangerous periods of impacts on Earth. According to the number and age of craters on Earth, we seem to suffer increased impacts every 36 million years. Uh oh, that’s a match.

In fact, one of these high points of comet activity would have been 65 million years – the same time that an asteroid strike wiped out the dinosaurs.

And here’s the bad news. According to their calculations, the Solar System will be passing through the galactic plane in the near future, and should see an increased risk of impact. Our risk of impact could increase 10-fold.

There might be a silver lining to the bounce, though. The impacts might have helped life spread across the galaxy.

While the “bounce” effect may have been bad news for dinosaurs, it may also have helped life to spread. The scientists suggest the impact may have thrown debris containing micro-organisms out into space and across the universe.

Centre director Professor Chandra Wickramasinghe said: “This is a seminal paper which places the comet-life interaction on a firm basis, and shows a mechanism by which life can be dispersed on a galactic scale.”

Here’s more info on the story from Bad Astronomy.

Original Source: Cardiff News Release

Posted on by Fraser Cain

Asteroid Impact Created a Worldwide Rain of Carbon Beads

When a large enough asteroid strikes the Earth, the devastation effects the entire globe. And the dinosaur-killing asteroid that smashed into the Yucatan peninsula 65 million years ago was no exception. According to researchers, just one outcome from the strike: carbon in the Earth’s crust was liquified and formed tiny beads that rained back down across the entire planet.

These beads are known to geologists as carbon cenospheres, and they’re produced during the burning of coal and crude oil. They’re a classic indicator of industrial activity. But 65 million years ago, there were no power plants, so scientists proposed that asteroid impact-driven forest fires could get hot enough to make them too.

As the asteroid struck, huge chunks of molten rock fell back to Earth, igniting forest fires across the planet. It’s here that scientists find evidence of charcoal from the fires, but not the cenospheres.

New evidence, reported in this month’s edition of the journal Geology, shows that natural fires can’t make the microscopic spheres.

Instead, the international team of researchers propose that they had to have been formed from an asteroid strike. A key additional piece of evidence is that the carbon cenospheres are deposited right next to a think layer of the element iridium.

It was this layer of iridium that helped to give scientists the evidence they needed to point to asteroids as the cause of the dinosaur extinction 65 million years ago. Since iridium is much more likely to be formed in the Solar System asteroids than in the Earth’s crust, a concentrated layer of the stuff had to come from off planet.

And the cenospheres have been discovered around the planet next to the iridium layer, in Canada, Spain, Denmark and New Zealand. The key discovery is that the cenospheres get smaller as you move away from the impact site. This matches the prediction that the heavier particles would rain back down to Earth closer to the impact, while the lightest particles would be carried across the entire planet.

The researchers were able to calculate the total amount of carbon injected into the atmosphere from an asteroid impact, and put the number at 900 trillion tonnes. This helps scientists get a better estimate of the impact size and damage.

Original Source: Indiana University

Posted on by Nancy Atkinson

Water in Interstellar Space

Water: it covers 70% of our own planet, it makes up 65% of our human bodies, and as far as we know, water seems to be essential for life. Water is also found in space, and in fact water ice is the most abundant solid material out there. But how did it get there, and how could water molecules possibly form in the freezing darkness of interstellar space? Japanese researchers trying to answer those questions say they have created water for the first time in conditions similar to interstellar space.

Water ice has been detected in our solar system on other planets and their moons, as well as in comets. A group of scientists at Japan’s Institute of Low Temperature Science at Hokkaido University say, “Since the solar system evolved from an interstellar molecular cloud, icy objects in the solar system originated from the water ice formed in the interstellar molecular cloud.” Their research was an attempt to gain an understanding of the origin of water molecules in interstellar clouds.

Water does form easily here in the warmth and abundance of Earth when oxygen and atomic hydrogen come together. But there’s not a lot of those elements floating around as gas in interstellar dust clouds. From their research, the group from Japan has concluded that water must form when atomic hydrogen interacts with frozen solid oxygen on a solid surface, such as dust grains in interstellar clouds.

They recreated this process by creating a layer of solid oxygen on an aluminum substrate at 10 degrees Kelvin and then added hydrogen. With infrared spectroscopy, they confirmed that both water and hydrogen peroxide formed, and in the right quantities to explain the abundance of water seen in interstellar clouds.

It’s interesting to note that the first water molecules in the universe must have started in this way, and that eventually led to water on Earth, then life, and then eventually people on Earth, who like to research, discuss and contemplate how it all began.

Original News Source: ArXiv, ArXiv blog

Posted on by Nancy Atkinson

XMM-Newton Discovers Part of Missing Matter in the Universe

We’re getting the numbers down pretty well now about how much we don’t know about the universe: Only about 5% of our universe consists of normal matter, made of atoms. The rest of our universe is composed of elusive matter that we don’t understand: dark matter (23%) and dark energy (72%). And of that 5% of normal matter, well, we don’t know what half of that is, either. All the stars, galaxies and gas observable in the universe account for less than a half of all the matter that should be around.

About 10 years ago, scientists predicted that the missing half of ‘ordinary’ or normal matter exists in the form of low-density gas, filling vast spaces between galaxies. The European Space Agency announced today that the orbiting X-ray observatory XMM-Newton has uncovered this low density, but high temperature gas.

The universe has been described as a cosmic web. The dense part of the web is made of clusters of galaxies, which are the largest objects in the universe. Astronomers suspected that low-density gas filled in the filaments of the web. But the low density of the gas has made it difficult to detect. With the XMM-Newton’s high sensitivity, astronomers have discovered the hottest parts of this gas.

Astronomers using XMM-Newton were observing a pair of galaxy clusters, Abell 222 and Abell 223, located 230 million light-years from Earth, when the images and spectra of the system revealed a bridge of hot gas connecting the clusters.

“The hot gas that we see in this bridge or filament is probably the hottest and densest part of the diffuse gas in the cosmic web, believed to constitute about half the baryonic matter in the universe,” says Norbert Werner from SRON Netherlands Institute for Space Research, leader of the team reporting the discovery.

The discovery of this hot gas will help better understand the evolution of the cosmic web.

“This is only the beginning,” said Werner. “To understand the distribution of the matter within the cosmic web, we have to see more systems like this one. And ultimately launch a dedicated space observatory to observe the cosmic web with a much higher sensitivity than possible with current missions. Our result allows to set up reliable requirements for those new missions.”

Original News Source: ESA Press Release

Posted on by Ian O'Neill

Digging for Dark Matter: The Large Underground Xenon (LUX) Detector

The Hubble Space Telescope distribution of dark matter - indirect observations (HST)

How do you catch a WIMP? No, I’m not talking about bullying the weakest kid in class, I’m talking about Weakly Interacting Massive Particles (those WIMPs). Well, it isn’t easy. Although they are “massive” by definition, they do not interact with the electromagnetic force (via photons) so they cannot be “seen” and they do not interact with the strong nuclear force, so they cannot be “felt” by atomic nuclei. If we cannot detect WIMPs via these two forces, how can we possibly ever hope to detect them? After all, WIMPs are theorized to be flying through the Earth without hitting anything, they are that weakly interacting. But sometimes, they might collide with atomic nuclei but only if they collide head-on. This is a very rare occurrence, but the Large Underground Xenon (LUX) detector will be buried 4,800 feet (1,463 meters, or nearly a mile) underground in an old South Dakota goldmine and scientists are hopeful that when an unlucky WIMP bumps into a xenon atom, a flash of light will be captured, signifying the first ever experimental evidence of dark matter…

Galaxies observed from Earth have some strange qualities. The biggest problem for cosmologists has been to explain why galaxies (including the Milky Way) appear to have more mass than can be observed by counting stars and accounting for interstellar dust alone. In fact, 96% of the Universe’s mass cannot be observed. 22% of this missing mass is thought to be held in “dark matter” (74% is held as “dark energy”). Dark matter is theorized to take on many forms. Massive Astronomical Compact Halo Objects (astronomical bodies containing ordinary baryonic material that cannot be observed; like neutron stars or orphaned planets), neutrinos and WIMPS all are thought to contribute toward this missing mass. Many experiments are in progress to detect each contributor. Black holes can be indirectly detected by observing the interactions in the centre of galaxies (or gravitational lensing effects), neutrinos can be detected in huge tanks of fluid buried deep underground, but how can WIMPs be detected? It seems a WIMP detector needs to take a leaf out of the neutrino detector’s books – it needs to start digging.

Super-Kamiokande, a neutrino detector in Japan, holds 50,000 tons of ultra pure water surrounded by light tubes (Super-Kamiokande)

To avoid interference from radiation such as cosmic rays, low energy detectors such as neutrino “telescopes” are buried well below the Earth’s surface. Old mine shafts make ideal candidates as the hole is already there for the instrumentation to be set up. Neutrino detectors are huge containers of water (or some other agent) with highly sensitive detectors positioned around the outside. One such example is the Super Kamiokande neutrino detector in Japan which contains a vast amount of ultra-purified water, weighing in at 50,000 tons (pictured left). As a weakly interacting neutrino hits a water molecule in the tank, a flash of Cherenkov radiation is emitted and a neutrino is detected. This is the basic principal behind the new Large Underground Xenon (LUX) detector that will use 600 pounds (272 kg) of liquid xenon suspended in a 25 foot high tank of pure water. If WIMPs exist beyond the realms of theory, it is hoped that these weakly interacting massive particles will collide head-on with a xenon atom, and like their light-weight cousins, emit a flash of light.

Robert Svoboda and Mani Tripathi, UC Davis professors, have secured $1.2 million in National Science Foundation (NSF) and U.S. Department of Energy funding for the project (this is 50% of the total required). When compared with the Large Hadron Collider (LHC) costing billions of Euros to build, LUX is a highly economic project considering the scope of what it might discover. Should there be experimental evidence of a WIMP interaction, the consequences will be enormous. We will be able to begin to understand the origins of WIMPs and their distribution as the Earth sweeps through the possible dark matter halo that is indirectly observed to exist in the Milky Way.

Detecting dark matter “would be the biggest deal since finding antimatter in the 1930s.” – Professor Mani Tripathi, LUX co-investigator, UC Davis.

The gold mine in South Dakota was closed in 2000 and in 2004 work began to develop the site into an underground laboratory. LUX will be the first large experiment to be housed there. It is hoped that the installation will start late summer, after water has been pumped out of the mine.

Original source: UC Davis News

Posted on by Nancy Atkinson

Another (Better) Opportunity to Send Your Name to Space

Kepler spacecraft. IMage credit: NASA

It’s a great idea, so all the missions might as well join in. Earlier today, Ian reported on how the Lunar Reconnaissance Orbiter mission is offering the chance for the public to ‘ride along’ to the moon by sending their names to be added to a computer chip which will be embedded on the spacecraft. Well, not to be outdone, the upcoming Kepler mission that will search for Earth-sized exoplanets is offering the same chance. But this is no sluff opportunity where you just fill in your name and you’re done: you’ve got to work a little and be creative! The Kepler folks would like you to also state in 100 words or less why you think the Kepler mission is important. I think that’s a great idea, and I’m going to add my name and statement right away. But there’s more reasons why I prefer the Kepler mission’s approach to sending your name to space:

Your name will be in an exciting Earth-trailing heliocentric orbit, going around the sun every 372.5 days.

This activity is done in association with the International Year of Astronomy 2009.

Your name will be on the spacecraft that will likely identify the first Earth-sized or smaller planet orbiting another star.

Your name will be launched on board a Delta II rocket.

Your name will be part of the mission that will determine the frequency of terrestrial and larger planets in or near the habitable zone of a wide variety of spectral types of stars.

Oh, the list goes on, but as you can see the Kepler mission will be THE mission to have your name be included.

So, here’s where you can add your name, as well as your statement of the importance of the Kepler mission. The deadline is November 1, 2008. And learn more about the mission here. Current plans are for a February 2009 launch for Kepler.

Original News Source: JPL press release