Here’s a round-up of recent science headlines we didn’t want you to miss!

Ancient Rivers

Without a smart phone or GPS device, how did early humans find their way out of Africa? A study published last week in PLoS One determines that ancient rivers, now covered by the Sahara Desert, provided habitable routes to follow.

Simulating paleoclimates in the region, the researchers found evidence of three major river systems that likely existed in North Africa 130,000–100,000 years ago, but are now largely buried by dune systems in the desert. When flowing, these rivers likely provided fertile habitats for animals and vegetation, creating “green corridors” across the region.

“It’s exciting to think that 100,000 years ago there were three huge rivers forcing their way across 1000-km of the Sahara desert to the Mediterranean—and that our ancestors could have walked alongside them,” says lead author Tom Coulthard of the University of Hull, UK.

Cosmic Beginnings?

Did life on Earth hail from Mars, as one researcher proposed last month, or comet collisions? Apparently, in both cases, it all has to do with the chemistry. Carl Zimmer, one of our favorite science writers, has a recent New York Times article about the chemistry needed to produce DNA from RNA. And while it doesn’t look like early Earth had those compounds, Mars might have.

Then, earlier this week, a study published in Nature Geoscience finds that the collision of icy comets with planetary bodies could result in the formation of complex amino acids, the building blocks of proteins (and life).

The researchers suggest that this process provides another piece to the puzzle of how life was kick-started on Earth, after a period of time between 4.5 and 3.8 billion years ago when the planet was being bombarded by comets and meteorites.

The team made their discovery by recreating the impact of a comet by firing projectiles through a large high-speed gun. This gun, located at the University of Kent, uses compressed gas to propel projectiles at speeds of 7.15 kilometers per second into targets of ice mixtures, which have a similar composition to comets. The resulting impact created amino acids such as glycine and D- and L-alanine. Sounds like a fun method of discovery…

Speaking of fun collisions, if you want more of them, the Morrison Planetarium at the Academy is featuring Cosmic Collisions in its current show rotation. From the our website:

Creative and destructive, dynamic and dazzling, collisions are a key mechanism in the evolution of the Universe.

Missing Mars Methane

One chemical Mars seems to be missing? Methane. The gas was sought as a possible sign of microbial life currently living on the seemingly barren world. However, despite earlier reports that NASA’s Mars rover, Curiosity, discovered methane on the red planet, NASA reports today in Science that none has been found.

Curiosity’s earlier evidence of methane detection turned out to be within leftover air from Earth. And previous reports of localized methane concentrations up to 45 parts per billion on Mars were based on observations from Earth and from orbit around Mars.

“It would have been exciting to find methane, but we have high confidence in our measurements,” says the report’s lead author, Chris Webster. “We measured repeatedly from Martian spring to late summer, but with no detection of methane.”

But don’t give up on microbial Martians just yet… “This important result will help direct our efforts to examine the possibility of life on Mars,” says NASA’s Michael Meyer. “It reduces the probability of current methane-producing Martian microbes, but this addresses only one type of microbial metabolism. As we know, there are many types of terrestrial microbes that don’t generate methane.”

Looking for extraterrestrial life? Next month’s Brilliant!Science festival can deliver it to you. Visit this page for more information.

Image: the Tunable Laser Spectrometer on-board Curiosity: NASA/JPL-Caltech

Roughly 70% water, Earth’s surface is covered with rivers, lakes, oceans, mud, and rain clouds. Scientists searching for alien life are searching for planets similar to our own, because experience tells us that life needs water in order to survive.

NASA’s Cassini spacecraft began photographing Titan, one of Saturn’s moons, in 2004. The pictures beamed back to Earth depict strange lakes and rivers. The European Space Agency (ESA)’s Huygens probe splashed into Titan’s mud in 2005, further convincing researchers that Titan was indeed “wet.”

The scientific community agrees that Titan appears Earth-like, but at temperatures around –290°F (–180°C), any water would be in the form of ice. Instead, astronomers believe any wetness on the surface of Titan is a combination of liquid methane, ethane, and other hard-to-freeze elements.

Apparently this moon doesn’t resemble Earth at all. Alex Hayes, a planetary scientist at Cornell University who works on the Cassini radar team, noticed something eerie while observing Saturn’s moon. “Where are all the waves?”

Wind, raindrops, and tides move Earth’s water in every direction. But Cassini has detected no wave action on Titan. It’s pretty strange, especially because, “[w]e know there is wind on Titan, the moon’s magnificent sand dunes prove it,” says Hayes.

Taking into account Titan’s gravity (one seventh that of Earth’s), the nature of fluids on its surface, and its dense atmosphere, Hayes and his colleagues calculated and published the speed needed for waves to form: only two miles per hour!

A strange puzzle, with even stranger solutions. Maybe the lakes are covered with tar, damping wave motion. Or they might be frozen. Or perhaps the wind hasn’t reached two miles per hour… yet.

Most of the lakes are located on Titan’s northern hemisphere, where it has been winter for a few years. The air during winter is colder and thicker, and may be the secret behind the missing waves.

If current climate models are correct, Cassini should be able to detect waves as Titan nears its summer solstice in 2017. Measurements and calculations of waves formed during the summer could tell us the chemical composition of Titan’s lakes… And reveal more about this Earth-like world so unlike Earth.

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA/JPL-Caltech/USGS

Space gold is even rarer than Earth gold, which makes the precious metal special—on our planet and in the Universe at large.

A team of astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) observed a special gamma-ray burst last month; these powerful phenomena appear to originate in cataclysmic events… and in this case it was likely the collision of two neutron stars.

Neutron stars are the dense remains of imploded stars: they are up to three times the mass of the Sun, condensed into the area of San Francisco.

Deep in their cores, regular stars create elements that are eventually spewed into space when the stars explode. Chris Impey, professor of astronomy at the University of Arizona, explains, “We know that stars make heavy elements, and late in their lives, they eject gas into the medium between stars so it can be part of subsequent stars and planets (and people).” Carbon, oxygen, nitrogen, and a host of other elements—even nickel and iron—all originate within different types of stars.

But it takes a collision between two neutron stars to create rare elements such as gold. The lead author of a recent paper, Edo Berger, describes the phenomenon by paraphrasing one of Carl Sagan’s famous quotes, “We are all star stuff, and our jewelry is colliding-star stuff.” And it makes sense—gold requires 79 protons, 79 electrons and 118 neutrons, a concoction only a dense neutron star would have the atomic supplies to produce.

When two particular neutron stars collided about 3.9 billion light years away from Earth, astronomers named the resulting gamma-ray burst GRB 130603B. Although the burst lasted only two-tenths of a second, a slowly fading infrared glow told the Harvard research team that the burst was particularly valuable.

“We estimate that the amount of gold produced and ejected during the merger of the two neutron stars may be as large as 10 moon masses—quite a lot of bling!” says Berger.

At today’s prices, the explosion would produce the equivalent of  $10,000,000,000,000,000,000,000,000,000 (10 octillion dollars). But don’t get too excited: these types of explosions happen in our galaxy only once every 10,000 years, and you might find it difficult to go and collect the loot.

This is big money, but there are additional implications of the neutron star collision.

“We’ve been looking for a ‘smoking gun’ to link a short gamma-ray burst with a neutron star collision. The radioactive glow from GRB 130603B may be that smoking gun,” explains Wen-fai Fong, a graduate student and a co-author of the paper.

Now that we have better evidence linking gamma-ray bursts and neutron star collisions, perhaps we can gain insight into the mystery radio bursts found outside our galaxy!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Credit: NASA/Dana Berry

The newest cosmic mystery: four distinct high-energy flashes! (Is the Universe trying to get our attention?) Astronomers are calling them Fast Radio Bursts, but we have yet to determine their origins.

Radio astronomers detected the first burst about six years ago, but it seemed so strange that many people thought it was a fluke. Dan Thornton, a PhD student at England’s University of Manchester and Australia’s Commonwealth Scientific and Industrial Research Organization, decided to investigate. He spent the next six years looking for these strange flashes.

So far Thornton and his team have found four radio bursts. Astonishingly, the flashes—taken from only a small section of the sky—indicate that there should be one of these signals going off every ten seconds.

“The bursts last only a tenth of the blink of an eye,” explained Max-Planck Institute Director and Manchester professor, Michael Kramer. “With current telescopes we need to be lucky to look at the right spot at the right time. But if we could view the sky with ‘radio eyes’ there would be flashes going off all over the sky every day.”

Astronomers have ruled out terrestrial sources for the Fast Radio Bursts and the origins in the high galactic latitudes suggest that they originate from beyond the Milky Way.

The brightness and distance of the mysterious flashes also hint that they originated when the Universe was about half its current age. “They have come such a long way that by the time they reach the Earth, the Parkes telescope would have to operate for one million years to collect enough to have the equivalent energy of a flying mosquito,” said Thornton.

Co-author Professor Matthew Bailes, from the Swinburne University of Technology in Melbourne, Australia, thinks that burst energies indicate that they come from events involving relativistic objects—maybe even from a type of neutron star called a magnetar. “Magnetars can give off more energy in a millisecond than our Sun does in 300,000 years and are a leading candidate for the burst.”

Astronomers have a lot more research to do before we can solve the radio burst puzzle, but the findings may also help crack some other astronomical mysteries. “We are still not sure about what makes up the space between galaxies, so we will be able to use these radio bursts like probes in order to understand more about some of the missing matter in the Universe,” said Ben Stappers, from Manchester’s School of Physics and Astronomy.

So these Fast Radio Bursts could even speed up cosmic discovery!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: Diceman Stephen West

Early last week I wrote an article about how new data from Voyager 1 shed light on the structure of the Sun’s heliosphere and solar wind. Just a few days after that, researchers announced evidence of Earth’s own space wind!

Scientists proposed the existence of a space wind surrounding Earth about 20 years ago, but direct detection has eluded scientists until now.

Earth is surrounded by a magnetic field that encloses our magnetosphere. The plasmasphere is the inner part of that magnetosphere, and it looks a giant donut made of electrically-charged particles called (as its name suggests) plasma.

The Sun’s magnetic activity can accelerate plasma toward Earth, which impacts our magnetosphere. During such solar storms, we have observed plumes of material transfer between the plasmasphere and the outer magnetosphere, but researchers also proposed the existence of a steady flow of plasma that occurs around the clock. After years of theoretical work, Iannis Dandouras of the Research Institute in Astrophysics and Planetology in Toulouse, France, has directly detected this wind in data from the European Space Agency’s Cluster spacecraft.

Dandouras measured the properties of charged particles in the plasmasphere to find that the forces governing plasma motion exist slightly out of balance, forming a steady wind.

“After long scrutiny of the data, there it was, a slow but steady wind, releasing about one kilogram of plasma every second into the outer magnetosphere. This corresponds to almost 90 tons every day. It was definitely one of the nicest surprises I’ve ever had!” said Dandouras.

Don’t worry, the plasmasphere won’t evaporate away: it also refills. Dandouras reassured everyone that “due to the plasmaspheric wind, supplying plasma—from the upper atmosphere below it—to refill the plasmasphere is like pouring matter into a leaky container.”

Michael Pinnock, Editor-in-Chief of Annales Geophysicae, recognizes the importance of the new result. “It is a very nice proof of the existence of the plasmaspheric wind. It’s a significant step forward in validating the theory. Models of the plasmasphere, whether for research purposes or space weather applications (e.g. GPS signal propagation) should now take this phenomenon into account.”

We can even apply our understanding of Earth’s plasmaspheric wind to other places. Why wouldn’t another planet such as Jupiter or Saturn experience the exact same phenomenon? The Solar System could be a very windy place!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA

“Earth calling. Can you hear us?”

Aliens (they are out there, right?) took too long to contact us. So now we’ve taken things into our own hands—to crowdsource “hailing messages”.

On June 17th, the Lone Signal project began transmitting messages written by the public from the Jamesburg Earth Station in central California. The first target: Gliese 526.

This red dwarf appears in the Catalog of Nearby Habitable Systems as a good candidate to support intelligent life. Red dwarfs are abundant and survive for a relatively long time. A potentially habitable planet would orbit this type of star closely, making it easier for astronomers to detect. And it lies only 17.6 light-years away from Earth, which makes it an even more appealing target!

So, great target, but what are we planning to send? Text messages from Earth? The idea is not so far-fetched, says Lone Signal co-founder Pierre Fabre. “We’re targeting the most logical, nearest stars now.” Scientists and engineers have sent carefully-encoded interstellar radio messages in the past, but now messages can be sent by anyone with Internet access.

“It’s never been the case that anyone on the face of the Earth can commune with the cosmos, and we are opening up that portal to the masses,” said Lone Signal chief marketing officer Ernesto Qualizza.

The 144-character messages are emitted in one of two adjacent radio beams, the other containing a looped message written in computer code by astronomer Michael Busch. His message describes Earth’s position in the Universe, the elements of the periodic table, and the structure of a hydrogen atom.

To detect our messages, aliens near Gliese 526 will need a radio interferometer like the ones at the Allen Telescope Array (ATA). If they decode our messages, perhaps they will also decide to respond.

Lone Signal wants to harness human curiosity to expand our knowledge of the Universe around us. Participate here!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: Jcolbyk

Within our solar system, few worlds have much in common with Earth. Sure, Venus is about the same size, and Mars may have once (billions of years ago) resembled Earth in terms of its chemistry… But in many ways, Titan, the largest moon of Saturn, seems to be the world most similar to home.

This moon remained a mystery from the time of its discovery in 1655 until the Cassini/Huygens mission managed to peer beneath its veil of thick clouds in 2004. And that mission has made astounding discoveries.

Underneath its obscuring atmosphere, Titan looks shockingly similar to Earth: the lander saw dunes and valleys, as well as beaches and most surprisingly, seas!

We caught the glint of sunlight off these massive methane lakes before, but another near pass by Cassini has allowed us to make a radar map of the topography of Titan’s surface to get a sense of the depth of these alien oceans. It also provided a chance to build upon our understanding of how mountains and valleys here on Earth affect weather patterns around them.

And Cassini has also helped us understand Titan’s unusual atmosphere. A recent NASA press release describes how the moon forms a chemical mix near the surface “like L.A. smog on steroids.” The presence of complex aerosols has long puzzled scientists, but Cassini’s data provided clues to identify the missing link in the process: polycyclic aromatic hydrocarbons (PAHs). (The Academy’s planetarium director recently blogged about a diagram that accompanied that press release.)

Cassini is approaching ten years in orbit around the ringed planet, and its work continues. A future objective is to determine if waves occur on any of Titan’s three largest seas, not too far a stretch given the observations of massive dunes sculpted by wind, but astronomers are still working to piece together the delicate balance of wind, temperature, chemical composition, and viscosity of these alien shores.

Every pass gives us more information about Titan’s clouds and the world beneath them—fleshing out our knowledge of this most familiar-seeming moon.

Josh Roberts is a program presenter and astronomer at the California Academy of Sciences. He also contributes content to Morrison Planetarium productions.

Image: NASA/JPL-Caltech/SSI

Earth’s neighborhood just got a little larger.

Astronomers thought that Earth was located on a spur of an arm of the Milky Way… until data from the Very Long Baseline Array telescopes suggested that we could be located closer to the center.

While it’s simple to observe a bird’s-eye view of other galaxies, models of the Milky Way are inaccurate due to Earth’s limited vantage point. We are attempting to measure an entire galaxy using only Earth’s narrow perspective, and at the center of our galaxy is a large bulge, blocking about half of the Milky Way from view.

To make the best model possible, astronomers use a technique called parallax. Measurements are taken from locations on either side of the sun to give multiple perspectives of our location in the sky. Then, astronomers use trigonometry to calculate where we might reside in comparison to distant objects.

At the center of the Milky Way is a supermassive black hole, whose gravitational pull is capable of keeping 200–400 billion stars in orbit around the galaxy. Measurements from NASA’s Spitzer Space Telescope revealed that these stars are oriented in two arms that spiral around the black hole.

“Based on both the distances and the space motions we measured, our Local Arm is not a spur,” said Alberto Sanna, a postdoctoral fellow with the Max-Planck Institute for Radio Astronomy (MPIFR). “It is a major structure, maybe a branch of the Perseus Arm, or possibly an independent arm segment.”

Sanna and his colleagues presented their research this week at the American Astronomical Society meeting, held in Indiana.

Astronomers are creating increasingly accurate models of the Milky Way and every new finding tells us more about the entire universe.

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA