Looking for Other Worlds

The search for exoplanets has gone from being an unlikely dream 20 years ago to being a booming area of research in astronomy and planetary science. The first true exoplanet discovery, according to NASA, was in 1994. Since then, 687 have been discovered, and more are being found all the time. This video from Cosmic Journeys takes you through some of the highlights of exoplanet discovery, particularly the search for Earth-like planets.

Hat tip to Ciro Villa on Google+

Planets Wandering Alone in Deep Space

Many science fiction plots use the idea of a deserted world wandering through space completely separated from its parent star. This dramatic set is a good place for intense action, but is it realistic? Even those worlds were out there, could we find them? A NASA press release claims not only are they there, but these worlds may even outnumber stars.

A forming solar system is a violent place. As the planets form around the young star, they start gravitationally pulling on each other. These tugs can send planets careening through the solar solar system, colliding into each other, or ejected from the system entirely. It's the planets that escaped that a team of astronomers from New Zealand and Japan were looking for.

Planets are not easy to find. The biggest problem is how small they are. The Earth may not seem like a small place, but compared with the vastness of space it is nothing more than a speck of dust. Normally we look for exoplanets by seeing the planet affect the light coming from their parent star in some way. So how could astronomer find these roaming worlds separated from their parent stars?

 The team of scientists used a 5.9 foot (1.8 meter) telescope to get their data. However, I would be surprised if any telescope could see even a large planet separated from its host star, so the astronomers got some help from gravity. When light passes through a lens, the speed the light is traveling changes. That then causes the light to chage direction. When light passes by a massive object, like a star or planet, that light is bent around the object changing its direction. The bigger the object the greater the effect. This effect allows astronomers to used massive objects in space, or even clusters of them, as natural lenses. This is called microlensing. This allowed the team to watch discover these planets as they magnified the light of background stars.

I really like this study for several reasons. They found something very exciting in these wandering worlds. They gave us a starting point in trying to figure out just how many of these lonely planets there are. They also were creative in discovering them using a subtle and elegant effect. Finally, they had their results confirmed by another independent team of astronomers before publication. This is kind of science that gets me excited do research and teach each day.

Have Scientists Found a Second Earth?

Ever since we stared finding exoplanets (planets orbiting a start other than our sun) back in 1992, the hunt has been on to find a Earth-like planet. Of course, the planets we found first were not the small rocky worlds like our own, but massive gaseous Jupiter-sized objects that are very close to their stars, appropriately called hot Jupiters. Over time, we got better at the techniques and have become able to find smaller and smaller planets farther and farther from their host stars. Now, have we finally found that long sought-after 'second Earth'?

So our first question is simply, what did they find? To really understand this situation, you need to understand the star this planet is orbiting. This is not a medium-large yellow star like our sun, but a much smaller red dwarf. Red dwarfs have about 1/3 of the mass of the sun and a luminosity of about 1.3% of our sun. This means a planet has to be much closer to the star then the Earth to our Sun to have any chance for life to survive.

That brings us to the planet Gliese 581g (such a creative name). Because of the method used to discover this planet, we know it has a minimum mass of about three times that of Earth, and it is unlikely that it is much larger than that. It is also the right distance away from the star to be in what's called the "habitable zone". This is the zone where a planet could potentially have liquid water on its surface. So far, so good.

Now is when things get tricky. There is still much astronomers don't know when it comes to rocky planets, and planets in general for that matter. Gliese 581g is large enough to hold on to an atmosphere, but atmospheres are tricky things to understand. Atmospheres are also hugely important for life. Mars and Venus can both be said to be in the habitable zone of our Sun, but because of Venus's overabundant atmosphere, and Mars' lack thereof, they are both devoid of life. To make things more complicated, Gliese 581g is probably tidally locked with its host star. This means that one side of the planet is in perpetual day while the other side never sees the sun.

Science rarely, if ever, gives us cut-and-dry answers. Does Gliese 581 harbor life, or would life even have a chance there? We can't be sure. What makes this discovery truly exciting, though, is the speed at which it happened. We have only been finding exoplanets for less than two decades and, of that time, our technology has only become sensitive enough to find small planets much more recently. We have really only begun to survey our neighbor stars in the galaxy and already we have found a planet that is a decent candidate to support life. If this trend continues, there could be millions of such worlds in our own galaxy alone. Think of the prospects if even just a small percentage of those worlds ever developed life.

I think it's time to kick up the planet hunt one more notch.

A Summer Review and Return from Break

This summer has turned out to be extremely busy, so we've been on hiatus here at Scientifica. As school gets back into session, we'll get back onto a regular posting schedule. There's no summer break for science news, though, so here's a quick review of stories from this summer.

• Viruses Harnessed to Split Water: A neat application of solar energy, which uses viruses as the means to split water using sunlight. The hydrogren produced can be stored, and used as a clean energy source later on.
  
• Earth Fossil Find May Lead to Martian Discoveries: New microfossils found in gypsum give astrobiologists a new place to look for evidence of life on Mars and other planets.
  
• Mica Minerals Key to the Origins of Life: Another new idea on how life could have gotten started. Instead of a lightning spark or a geothermal soup, the thin, organized sheets of mica could have provided an ideal environment for the first living things to appear.
  
• The Moon is Shrinking: Scarps and ridges on the Moon's surface are changing, suggesting that the Moon is shrinking as its interior cools off.
  
• Oldest Material in the Solar System Found: A new test of a meteorite found in Morocco suggests that our Solar System may be as much as 2 million years older than previously thought.
  
• 'Dry Water': This peculiar combination of silica and water could be used to contain harmful industrial byproducts and greenhouse gases, or to kick-start chemical reactions.
  
• When Galaxies Collide- How the First Super-Massive Black Holes were Born: Computer models suggest that, within the first billion years after the Big Bang, young galaxies crashed into one another, and their central black holes merged into super-massive black holes.
  
• New Solar System Discovered: It has at least 5 planets, all about the size of Neptunes, and possibly another 2, one similarly sized to Saturn, the other closer to Earth in scale. It's the biggest exoplanet system found to date.

These are just a few of the highlights from the past few months. There were a ton other fascinating discoveries, studies, innovations, and ideas that popped up, some of which I'll discuss in more detail in the next few weeks. For now, I hope you find these stories as interesting as I did.

Direct Spectrum of an Exoplanet taken for the First Time

Analyzing the spectrum of light coming from a star or planet gives us a huge insight into the composition and environment of that object. If we ever find a exoplanet we think could harbor life, one of the first things we will want to do is get a light spectrum. The would potentially allow us to find free oxygen (a distinct signature of life) in its atmosphere. This makes developing the technique of attaining exoplanet spectrum a huge necessity.

The breakthrough was done on a gas giant orbiting the star HR 8799, which is just slightly larger than our own sun. What makes this measurement special is not that we got a spectrum, but that we got a spectrum straight from the planet itself. In the past we have analyzed the light from a star, that passed through the atmosphere of its exoplanet. While this is still a valid technique, it is only possible to do with planets that have the right orientation to our own solar system. Because only a small fraction of planets have such an orientation, this opens the door to studying the growing number of exoplanets. This planet is extremely hot at about 1,800 degrees Fahrenheit, causing it to pouring out infrared light. This made it a great target for trying this technique, but it was still no walk in the park. “It's like trying to see what a candle is made of, by observing it next to a blinding 300 Watt lamp – from a distance of 2 kilometres [1.3 miles],” said Markus Janson of the University of Toronto, lead author of the paper.

As is almost to be expected with the first results from any new technique, the results from this spectrum were totally unexpected. This planet's spectrum didn't match any of the models we had for gas giants. The current thinking is that this planet was one the verge of becoming a brown dwarf star. With roughly 10 times the mass of Jupiter, it is probably still emitting heat from when it was formed. The composition is also not what was expected from previous models. This once again show how young our models of solar system formation really are.

As we continue to do this on more planets and refine the process, I'm sure we will continue to find things that surprise us. I still think the most exciting part of all this is the ability to use this to find other life in the universe. We will have to wait and see what the future holds, but I think it is promising.

For More Information see the European Southern Observatory site
Image Credit: ESO/M. Janson

Kepler Finds Weird New Exoplanets

The Kepler Space Telescope is a attempt to find potentially habitable worlds around other stars. Those discoveries are still probably a little ways off, but Kepler has found its first 5 planets. These findings were anounced on Monday, and provide new mysteries for scientists to solve.

The planets Kepler found are called "hot Jupiters". This is because they are approximately the same size as Jupiter in our own solar system, but very close to their parent stars. “We expected Jupiter-size planets in short orbits to be the first planets Kepler could detect,” said Jon Morse, director of the Astrophysics Division at NASA. “It’s only a matter of time before more Kepler observations lead to smaller planets with longer period orbits, coming closer and closer to the discovery of the first Earth analog.” Hot is actually a bit of a understatement in this case since they are well over 2000 degrees Fahrenheit. Still, these 5 are the first to be confirmed planets out of over 100 candidates that have been found. Most of the over 400 exo-planets we have found to date are hot Jupiters, but Kepler's new planets have some unique oddities.

Saturn is the least dense body in our solar system and would float in water (assuming you can find a big enough lake). One of the new planets discovered by Kepler puts Saturn to shame, having a density close to styrofoam. This makes it the least dense planet ever found and poses the mystery of how it formed. Other objects found appear to be planet like objects, only they are hotter than the stars they are orbiting. Ground based observations are looking into these objects and I am curious what they will conclude.

Right now the Kepler planet count is at 5, but this is just the start. These results push the limits of what kinds of planets exist in the universe, and that is exciting. I think this is just a taste of what is to come.

Sources:
Wired
Universe Today

Image Credit: NASA

Some Cool Astronomy Pareidolia

Pareidolia is our brains ability to see familiar images in random noise. This is what gives us the images of Jesus appearing in everything from grilled cheese to grease stains. I have always thought that pareidolia is also really fun. Astronomy is famous for its great imagery. As would be expected, some of the images have a familiar ring to them.