Billions of Earth-size planets in Milky Way
Source: Agencies |
January 9, 2013, Wednesday
|
Print Edition
Print Edition
OUR Milky Way is home to at least 17 billion planets that are similar in size to Earth, a new estimate suggests. That's more than two Earth-size planets for every person on the globe.
Just how many are located in the sweet spot where water could exist is "simply too early to call," said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics.
It's the first reliable tally of the number of worlds outside the solar system that are the size of Earth.
The sheer number of Earth-size planets gives astronomers a starting point to narrow down which ones are in the habitable zone.
Fressin and his team came up with their figure by conducting a fresh analysis of data collected by NASA's Kepler spacecraft, which was launched in 2009 to track down other Earths. They estimated at least one in six stars in the galaxy hosts a planet the size of ours, translating to at least 17 billion Earth-size worlds.
Using a different method, a team from the University of California, Berkeley and University of Hawaii separately came up with a similar estimate. They calculated 17 percent of distant stars have planets that are the same size as Earth or slightly larger.
Meanwhile, the Kepler spacecraft continues to spot planets as they pass between Earth and the star they orbit. It found 461 new candidate planets, bringing the total to 2,740 potential planets.
Just how many are located in the sweet spot where water could exist is "simply too early to call," said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics.
It's the first reliable tally of the number of worlds outside the solar system that are the size of Earth.
The sheer number of Earth-size planets gives astronomers a starting point to narrow down which ones are in the habitable zone.
Fressin and his team came up with their figure by conducting a fresh analysis of data collected by NASA's Kepler spacecraft, which was launched in 2009 to track down other Earths. They estimated at least one in six stars in the galaxy hosts a planet the size of ours, translating to at least 17 billion Earth-size worlds.
Using a different method, a team from the University of California, Berkeley and University of Hawaii separately came up with a similar estimate. They calculated 17 percent of distant stars have planets that are the same size as Earth or slightly larger.
Meanwhile, the Kepler spacecraft continues to spot planets as they pass between Earth and the star they orbit. It found 461 new candidate planets, bringing the total to 2,740 potential planets.
- About Us
- |
- Terms of Use
- |
-
RSS - |
- Privacy Policy
- |
- Contact Us
- |
- Shanghai Call Center: 962288
- |
- Tip-off hotline: 52920043
- 沪ICP证：沪ICP备05050403号-1
- |
- 互联网新闻信息服务许可证：31120180004
- |
- 网络视听许可证：0909346
- |
- 广播电视节目制作许可证：沪字第354号
- |
- 增值电信业务经营许可证：沪B2-20120012
Copyright © 1999- Shanghai Daily. All rights reserved.Preferably viewed with Internet Explorer 8 or newer browsers.
