News / Science & Technology

Milky Way Could Contain 100 Billion Planets

A section of the Milky Way as seen by the Kepler telescope.
A section of the Milky Way as seen by the Kepler telescope.
It seems like hardly a week goes by without another planet being discovered in some far off stellar system, but a new study, released by the California Institute of Technology, indicates there will likely be many, many more such discoveries.

The Caltech team made this conclusion based on analyzing the planets orbiting the Kepler-32 star, which contains five planets and which the scientists say is representative of the vast majority of stars in our galaxy. Kepler-32 is classified as an M dwarf, and scientists say three out of every four stars in the galaxy are M dwarfs, also known as red dwarfs.

"There's at least 100 billion planets in the galaxy—just our galaxy," says John Johnson, assistant professor of planetary astronomy at Caltech and coauthor of the study, which was recently accepted for publication in the Astrophysical Journal. "That's mind-boggling."

Scientists say their estimate of 100 billion planets is conservative because it doesn’t take into account planets which may be orbiting further away from M dwarfs or planets orbiting other types of stars.

According to the scientists, Kepler-32’s five planets, which were detected by the Kepler space telescope, are similar in size to Earth. They are also similar to other planets discovered around other M dwarf stars. They all orbit very close to their star, no further than one-third the distance Mercury orbits our Sun. This is typical of M dwarf systems, Johnson said.

While the planets may resemble Earth in size, the Kepler-32 system differs from the Solar System. The star is much cooler than the sun, has only five percent of its brightness and is only half the size.

Johnson said an alternate headline for the discovery is just how much of a “weirdo” our own solar system is compared to the vast majority of systems in the galaxy.

Still, the Kepler-32 star system does have what is called a “habitable zone,” where liquid water could exist. In the Kepler-32 system, only the outermost planet is in that zone,  but Johnson said it likely resembles Neptune and would likely not support life.

Because of its orientation, Kepler-32 presents itself as a great opportunity to study as all the planets’ orbits are in a plane and can be viewed edge-on as they briefly block the light from the star. These small changes in light allow scientists to determine the planets’ characteristics such as size and orbital speed.

"I usually try not to call things 'Rosetta stones,' but this is as close to a Rosetta stone as anything I've seen," Johnson says. "It's like unlocking a language that we're trying to understand—the language of planet formation."

Johnson said the next big question would be if any of the planets in the habitable zones around M dwarf stars could support life.

“There are 20 different factors on Earth, and we don’t know how to rank them,” Johnson said. “Do we need a moon? It’s important. How critical? Do you have to have plate tectonics?”

Johnson said those questions are best suited for climate scientists and geologists.

“Until we have the ability to study those things, we won’t know if they’re hospitable,” he said. “If you were looking at our Solar System from an alien world, you might write a press release saying you’d discovered two planets in the habitable zone. Venus is in the habitable zone, but it’s not a good vacation spot.”

You May Like

Guatemala Mudslide Death Toll Rises to 86

Death toll is expected to continue to rise as emergency crews dig through tons of earth for an estimated 350 people still missing More

Debris Found in Search for Missing Ship

Objects located Sunday have not yet been confirmed to be from the 240 meter container ship, El Faro, which disappeared in the eye of Hurricane Joaquin, according to US Coast Guard More

Survivor: Gunman Spared 'Lucky One' to Give Police Message

Law enforcement official says a manifesto of several pages was recovered; contents not revealed More

This forum has been closed.
Comment Sorting
by: Ciaran Mulcahy. from: Dublin, Ireland.
January 07, 2013 6:50 AM
Unless one believes in a religious explanation for life, and its creation; or, even, that human existance is so rare, that the fact that what we regard as human life, developed at all, is miraculous; we 'have' to be able to prove that our planet is 'not' the only place where human-life exists.

Does recent information sent back from electronic equipment on Mars, aid us to one day believe, that human-life on this planet, 'could' have moved to Earth, from Mars?.

Something like two, or three decades ago, scientists and astronomers believed, at least for a while, that radio-telescopes had detected the reception of a decipherable alphabetical letter-symbol, which they believed, could have been real, and extra-terrestrial in origin. What part of the universe, and its galaxies, was it detected as possibly originating from; and in what Broadcast-Frequency Range?. Could the 'apparent' transmission of an 'apparent' random alphabetical-letter, been due to a random burst, from a known, or, equally, unknown gas, or liquid, from some undetermined source?

by: sifandy from: Indonesia
January 06, 2013 9:47 AM
wow amazing, that very wonderfull

by: ReadIt from: Miami
January 06, 2013 12:15 AM
The Universe is a fractal, organic system, which reproduces complementary, social networks of energy and information that self-organize themselves in bigger, self-similar scales which constantly undergo endless cycles of creation and destruction. All entities are 'cellular societies' organized through energy and information networks that bring about processes of social evolution of parts into wholes. All sciences share the laws of duality, systems and organicism since the properties of energy and information remain invariant in all the scales of reality. The result is the fractal structure of the Universe, a superorganism made of smaller superorganisms. :-)

by: James from: Nebraska
January 04, 2013 9:03 PM
Gazing is the point. One will learn where it all comes from by studying evidence, not mysticism.

And shadows on the wall? No. They are looking at actual star systems that can be demonstrated to exist.

by: Rob Swift from: Great Britain
January 04, 2013 6:21 PM
One day these people will get clued up. They marvel at the material universe without grasping the overall picture. They gaze at stars like they are gazing at a screen, without grasping how, or from where, it is all projected . They marvel at mere shadows on the wall.

by: Dan from: Utah
January 04, 2013 4:57 PM
So many possibilities, so little time, and the question of the century… with so many planets in the universe, what is the possibility of “intelligent” life on one of them? Let’s not fool around and assume this intelligent life will be about where humans are or at least close to it. Let’s imagine there is one out there that has been around for hundreds of millions of years. This is an intelligent species that has learned not to destroy itself because it still exists… with all that knowledge, surely they would know how to do a good job of it if they were so inclined. Therefore, we have a species that is at least at peace with itself and most likely others. We are talking about hundreds of millions of years beyond where we are today in knowledge and wisdom. Hmmm, I wonder if we would consider them gods if we were to meet them or perhaps we have. Perhaps that is why we are the dominant species on earth, except for all those pesky bacteria, that is. 

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Russia’s Syria Involvement Raising Concerns in Europei
Luis Ramirez
October 02, 2015 4:45 PM
European nations are joining the United States in demanding that Russia stop targeting opposition groups other than the Islamic State militants as Russian warplanes continue to conduct raids in Syria. The demand came in a statement from Britain, France, Germany, Qatar, Saudi Arabia, Turkey and the United States Friday. VOA Europe correspondent Luis Ramirez reports.

Video Russia’s Syria Involvement Raising Concerns in Europe

European nations are joining the United States in demanding that Russia stop targeting opposition groups other than the Islamic State militants as Russian warplanes continue to conduct raids in Syria. The demand came in a statement from Britain, France, Germany, Qatar, Saudi Arabia, Turkey and the United States Friday. VOA Europe correspondent Luis Ramirez reports.

Video First Self-Driving Truck Debuts on European Highways

The first automated semi-trailer truck started its maiden voyage Friday, Oct. 2, on a European highway. The Daimler truck called 'Actros' is the first potentially mass-produced truck whose driver will be required only to monitor the situation, similar to the role of an airline captain while the plane is in autopilot mode. VOA’s George Putic reports.

Video Nano-tech Filter Cleans Dirty Water

Access to clean water is a problem for hundreds of millions of people around the world. Now, a scientist and chemical engineer in Tanzania (in East Africa) is working to change that by creating an innovative water filter that makes dirty water safe. VOA’s Deborah Block has the story.

Video Demand Rising for Organic Produce in Cambodia

In Cambodia, where rice has long been the main cash crop, farmers are being encouraged to turn to vegetables to satisfy the growing demand for locally produced organic farm products. Daniel de Carteret has more from Phnom Penh.

Video Migrant Influx Costs Europe, But Economy Could Benefit

The influx of hundreds of thousands of refugees and migrants is testing Europe’s ability to respond – especially in the poorer Balkan states. But some analysts argue that Europe will benefit by welcoming the huge numbers of young people – many of them well educated and willing to work. Henry Ridgwell reports from London.

Video Botanists Grow Furniture, with Pruning Shears

For something a bit out of the ordinary to furnish your home, why not consider wooden chairs, crafted by nature, with a little help from some British botanists with an eye for design. VOA’s Jessica Berman reports.

Video New Fabric Helps Fight Dust-Related Allergies

Many people around the world suffer from dust-related allergies, caused mainly by tiny mites that live in bed linen. Polish scientists report they have successfully tested a fabric that is impenetrable to the microscopic creatures. VOA’s George Putic has more.

Video Burkina Faso's Economy Deeply Affected by Political Turmoil

Political turmoil in Burkina Faso over the past year has taken a toll on the economy. The transitional government is reporting nearly $70 million in losses in the ten days that followed a short-lived coup by members of the presidential guard earlier this month. The crisis shut businesses and workers went on strike. With elections on the horizon, Emilie Iob reports on what a return to political stability can do for the country's economic recovery.

Video Fleeing Violence, Some Syrians Find Refuge in Irbil

As Syrians continue to flee their country’s unrest to seek new lives in safer places, VOA Persian Service reporter Shepol Abbassi visited Irbil, where a number Syrians have taken refuge. During the religious holidy of Eid al-Adha, the city largely shut down, as temperatures soared. Amy Katz narrates his report.

Video Nigeria’s Wecyclers Work for Reusable Future in Lagos

The streets and lagoons of Africa's largest city - Lagos, Nigeria - are often clogged with trash, almost none of which gets recycled. One company is trying to change that. Chris Stein reports for VOA from Lagos.

Video Sketch Artist Helps Catch Criminals, Gives a Face to Deceased

Police often face the problem of trying to find a crime suspect based on general descriptions that could fit hundreds of people in the vicinity of the crime. In these cases, an artist can use information from witnesses to sketch a likeness that police can show the public via newspapers and television. But, as VOA’s Greg Flakus reports from Houston, such sketches can also help bring back faces of the dead.

Video Thailand Set to Build China-like Internet Firewall

Thai authorities are planning to tighten control over the Internet, creating a single international access point so they can better monitor content. VOA Correspondent Steve Herman reports from Bangkok on what is being called Thailand’s own "Great Firewall."

Video Croatian Town’s War History Evokes Empathy for Migrants

As thousands of Afghanistan, Iraqi and Syrian migrants pass through Croatia, locals are reminded of their own experiences with war and refugees in the 1990s. VOA's Daniel Schearf reports from the town of Vukovar, where wartime scars still are visible today.

Video Long Drought Affecting California’s Sequoias

California is suffering under a historic four-year drought and scientists say even the state's famed sequoia trees are feeling the pain. The National Park Service has started detailed research to see how it can help the oldest living things on earth survive. VOA’s George Putic reports.

VOA Blogs