by Benjamin Vermette
Alien life in the solar system? A month of discoveries leaves unanswered questions
In the hunt for extraterrestrial life, we’ve turned to our own cosmic backyard.
Last month saw a series of discoveries that offer tantalizing hints of life in our solar system.
On March 6, NASA published a study showing strong evidence that Mars once had a vast ocean comparable to our Arctic Ocean. Up to a fifth of the planet may have been covered in water for millions of years. In other words: enough time for life to evolve.
The discovery was made by scientists at NASA’s Goddard Space Flight Centre in Maryland, using an infrared telescope to study water molecules on the planet. Their observations point to the historic presence of an ocean in the Northern Hemisphere that would have been two kilometers deep in places.
Today, however, the planet is a dry and barren rock. Most of the water has long since gone into space, or possibly gone into the ground.
But it isn’t just water that’s been found on Mars.
Last December NASA’s car-sized Curiosity rover detected atmospheric methane on the planet’s surface — a significant discovery, since methane is a gas that’s produced by living organisms on Earth. It’s also thought Saturn’s moon Titan may have oceans of liquid methane, which could support life.
On March 11, astronomers working with NASA’s Cassini spacecraft announced the discovery of a warm ocean on the south pole of Enceladus, another of Saturn’s moons. The water’s warm temperature is principally due to gravitational friction from the pull of Saturn and its other moons, resulting in hydrothermal activity.
Jonathan Lunine, a planetary scientist at Cornell University who works with Cassini, likened the hydrothermal activity to the environment that gave rise to life on Earth. The discovery pits it as the number-one contender for alien life in our solar system.
A day later, officials manning the Hubble Space Telescope declared the largest moon in our solar system — Ganymede, which orbits Jupiter — may be hiding an ocean 150 km below its crust.
Then, on March 24, it was announced that Curiosity had found another ingredient for life on Mars: nitrogen. Making up 80 per cent of our own atmosphere, nitrogen is a gas that living organisms can’t do without.
Despite these exciting clues, we still can’t make any hard and fast statements about extra-terrestrial life in our solar system. We can, however, add Enceladus, Mars and Ganymede to the list of 20 other places – and counting – where water has been found in our solar system.
Watching a supernova explode – multiple times
Early last month, NASA released a shot of something extraordinary in a galaxy far, far away: a supernova — otherwise known as an exploding star.
What made this shot so special? It’s the first time that the explosion has been captured multiple times at once. That’s right, the four pricks of light that are pointed out in the image below are actually the same star.
But how can we pick one star out of a multi-billion-star galaxy, let alone see it four times? Thanks to the process of nuclear fusion, the same process that allows our sun to produce light and heat, we can. Stars fuse hydrogen into helium, helium into carbon, carbon into oxygen, neon, and other heavier elements: this process is known as nuclear fusion. When a massive star runs out of fuel, it explodes. While exploding, it releases enormous amounts of energy and material into space. This is what we call a supernova. A supernova is therefore brighter than an entire galaxy; this is why we can pick one star out of the billions surrounding it in space.
Why did this one show up four times simultaneously? As Albert Einstein proved, big objects can bend space, the way our sun bends space around itself due to its gigantic gravity and mass.
Imagine a big bowling ball on a big sheet of paper, where the bowling ball is the object of significant mass and the sheet of paper represents space. You can imagine the curve that would take the sheet of paper. This is exactly the shape space takes around stars, black holes and galaxies. When light passes through curved spaces, it bends.
The supernova in the picture is in a spiral galaxy more than 9 billion light-years from Earth. On its 9-billion-year trip to Earth, the light from the star passed through a galaxy cluster, which meant the light bent.
Picture this while looking at the image: some of the star’s light was not headed towards us and if it had continued its route straight ahead, the Hubble Space Telescope wouldn’t have seen the supernova. But while passing through the galaxy cluster, the supernova’s light was bent towards us because of the high gravity of that cluster (due to the mass of stars and gases, as well as dark matter).
This effect — known as gravitational lensing — is very rare. This was one of the first times a supernova has been seen under the effect.
“It really threw me for a loop when I spotted the four images surrounding the galaxy — it was a complete surprise,” said Dr. Patrick Kelly of the University of California, who authored a recent paper discussing the phenomena.
March 27 saw the liftoff of a year-long mission to the International Space Station. NASA astronaut Scott Kelly and Russians cosmonauts Mikhail Kornienko and Gennady Padalka tool off on board a Soyuz spacecraft. They’ll return home March 2016.
NASA administrator Charles Bolden says the mission is critical to advancing plans to one day send a man to Mars. “We’ll gain new, detailed insights on the ways long-duration spaceflight affects the human body,” he said. The mission will place Padalka in the number-one spot for most time spent in space by anyone in history.
Liftoff, part 2
March 11 saw the testing of NASA’s Space Launch System, a launch vehicle that will hopefully put a man back on the moon, and one day on Mars. The rocket is designed to carry two extra boosters powered by solid fuel; last month’s testing used one of these boosters.
The test took place in the desert of Utah, where a stationary firing of the rocket was performed. The test, known as Qualification Motor 1, or QM-1, lasted two minutes and six seconds, with the booster flaming out of schedule a little bit.
Found: the largest and brightest black hole ever
It’s estimated our solar system is 13.5 billion years old and about a billion years after that a monster black hole formed.
But it wasn’t until earlier this year that scientists discovered it. A black hole is a region of space with such a strong gravitational pull that no particle can escape — not even light particles.
This particular black hole has a mass 12 billion times that of our sun, making it the largest and most luminous one ever discovered. It’s known as a supermassive black hole (SMBH). It’s believed SMBHs lurk in the center of almost every large galaxy.
But how can the biggest black hole also be the brightest one?
Although you can’t actually see a black hole, you can see what’s happening around it. As matter is pulled in towards a black hole, the gravitational pull creates energy, which in turn produces x-ray emissions. The bigger it is, the greater the potential that matter being sucked in will leave a colossal visual footprint.
The discovery of the SMBH, known as SDSS J010013.02+280225.8, has left some scientists rethinking the early period of our cosmos. “Forming such a large black hole so quickly is hard to interpret with current theories,” said Fuyan Bian, of the Australian National University. “Current theory is for a limit to how fast a black hole can grow, but this black hole is too large for that theory.”
There’s no indication yet on how the discovery may alter that theory.
Demystified: Earth’s (other) moon
In case you were wondering, the Earth does not, in fact, have a second moon.
Various news sources, such as the U.K.’s Daily Mail, have recently taken to describing Asteroid 2014 OL339 as Earth’s other “moon”. Let’s take a closer look at Asteroid 2014 OL339. Is it turning around the Earth? Yes. But is it actually orbiting the Earth (the way our moon does)? No.
Asteroid 2014 OL339 is actually orbiting the sun along a highly elliptical (oval-shaped) orbit that sends it past the Earth, Mercury and Venus. By contrast, our moon does orbit Earth; they interact through mutual gravitational attraction.
In other words, there’s a difference between orbiting Earth and simply turning around Earth. So, why the impression that the asteroid is in Earth’s “orbit”? It turns out 2014 OL339 orbits the sun in 364.92 days. Which means that, by coincidence, it orbits the sun in roughly the same time that Earth does.
So no, Earth doesn’t have a second quasi-moon. But you knew that from grade school, right?
A planet with … four suns?
Do you remember the beginning of the original Star Wars movie? Early in the film, a young Luke Skywalker, soon to leave his home planet, is seen wistfully observing a particularly stunning sunset — a sunset, as it happened — with two suns.
Turns out that this detail wasn’t simply the stuff of fantasy. While our solar system only has one parent star (the sun) two-star systems are actually much more common. Triple-star systems are very rare, but not unheard of. And four-star systems? Even more so.
In early March, researchers from the Palomar Observatory in California published their findings on a planet that’s part of a four-star system. It’s only the second planet ever to be found in such a system. Dubbed 30 Ari, it’s located in the constellation Aries. It’s also enormous: about 10 times the mass of Jupiter.
Unfortunately, it’s too hot to be habitable, due to its close proximity to the system’s primary star. It was previously thought that the system only had three stars, but thanks to advances in observational techniques, the fourth was recently confirmed. Recent studies may indicate that planets in quadruple star systems are less rare than previously thought. “About four percent of solar-type stars are in quadruple systems,” says Andrei Tokovinin of the Cerro Tololo Inter-American Observatory in Chile.
The first four-star planet, KIC-4862625, was discovered in 2013 by amateur scientists using public data from NASA’s Kepler mission.