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

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

The galaxy, dubbed with the melodic name MACS 1149-JD, was spotted using  the combined power of NASA’s Spitzer and Hubble space telescopes as well as the phenomenon of gravitational lensing – using the gravity of nearer massive galaxies to bend and magnify the light of more distant ones behind them, which would otherwise remain invisible.

Small and compact, the galaxy appears to contain the equivalent of only about 1 percent of the Milky Way’s mass. The galaxy is quite young, only about 200 million years old, but we see it far back in time, when the Universe was quite young. (Imagine looking at an old photograph of your great grandparents: an old image showing a perhaps quite young couple.)  Light from the young galaxy captured by the orbiting observatories shone forth when the 13.7-billion-year-old Universe was just 500 million years old.

MACS 1149-JD existed during an important era when the Universe began to emerge from the cosmic Dark Ages. During this period, the Universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens up a window into the deepest, remotest periods of cosmic history.

“This galaxy is the most distant object we have ever observed with high confidence,” says Wei Zheng, lead researcher on a paper appearing in Nature this week. “Future work involving this galaxy—as well as others like it that we hope to find—will allow us to study the universe’s earliest objects and how the Dark Ages ended.”

According to leading cosmological theories, the first galaxies should have started out tiny like MACS 1149-JD. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

These first galaxies likely played the dominant role in the “epoch of reionization,” the event that signaled the demise of the universe’s dark ages. This epoch began about 400,000 years after the Big Bang when neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the Universe to ionize, or lose an electron, a state that the gas has remained in since that time.

Astronomers plan to study the rise of the first stars and galaxies and the epoch of reionization with the successor to both Hubble and Spitzer, NASA’s James Webb Telescope, which is scheduled for launch in 2018. The newly described distant galaxy likely will be a prime target.

Image: NASA/ESA/STScI/JHU