Introduction
Centuries ago, it was considered heresy to suggest that the Earth was not the centre of the universe, let alone that there may be other Earths in space! Nowadays, astronomers know for sure that there are planets orbiting nearby stars, although none have shown any sign of life. However, scientists are now hopeful that somewhere in the countless planetary systems in the universe, Earth has a twin.
Viewing other planets
Until recently, astronomers had no way of telling for sure if other stars had planets. Extrasolar planets are difficult to see because they are dwarfed by the light from their parent star. However, in 1995, astronomers suggested that a star with an orbiting planet would appear to wobble very slightly when viewed through a telescope. They believed that this was because the gravitational pull of the planet would cause the star's light to bend and thus change color. Extrasolar planets can also be detected by looking for a slight decrease in the brightness as a planet comes between them and telescopes on Earth.
Space Visits
With today's tech, we are unable to detect any but the closest and largest extrasolar planets.Planets the size of Earth have too small a gravitational pull to affect their parent stars enough for astronomers to notice. Even if an Earth-sized planet passed in front of its star, the drop in brightness would barely be perceptible through Earth's atmosphere. NASA's planned Terrestrial Planet Finder is due to search the brightest 1,000 stars in the solar system between 2010 and 2020. It will be able to see Earth-sized planets and even be able to detect what their atmospheres are like.
Other Earths
In 1600, an astronomer named Giordano Bruno was burned at the stake as punishment for heresy. His crime was to suggest that around each star there may very well be planets like Earth, each with a Jesus like figure. We now know for sure that there are potentially billions of extrasolar planets in our galaxy alone, but none discovered so far have resembled Earth. In fact, the solar systems found are shockingly different to our own, formed mainly of giant planets. Orbiting Tau Bootis is a planet four times bigger than Jupiter.It is so closer to its parent star that astronomers think that its cloud may be formed from vapourized rock.
(click here to get the image)
Some important facts
1) Most planets that astronomers have found so far are big as Jupiter or even bigger. Most are also very close to their parent star and are very hot.
2) Most of the extrasolar planets found to date have highly elliptical orbits that take them very close to their suns, then very far away. This means water could not remain in liquid form.
Facts and figures
First extrasolar planets discovered :
Parent star : Mass of planet
51 Pegasi 150 x Earth
55 Cancri 270 x Earth
47 Ursae Majoris 890 x Earth
Tau Bootes 1,230 x Earth
Upsilon Andromedae 220 x Earth
70 Virginis 2,100 x Earth
16 Cygni B 480 x Earth
Rho Coronae Borealis 350 x Earth
Gliese 876,670 x Earth
Centuries ago, it was considered heresy to suggest that the Earth was not the centre of the universe, let alone that there may be other Earths in space! Nowadays, astronomers know for sure that there are planets orbiting nearby stars, although none have shown any sign of life. However, scientists are now hopeful that somewhere in the countless planetary systems in the universe, Earth has a twin.
Viewing other planets
Until recently, astronomers had no way of telling for sure if other stars had planets. Extrasolar planets are difficult to see because they are dwarfed by the light from their parent star. However, in 1995, astronomers suggested that a star with an orbiting planet would appear to wobble very slightly when viewed through a telescope. They believed that this was because the gravitational pull of the planet would cause the star's light to bend and thus change color. Extrasolar planets can also be detected by looking for a slight decrease in the brightness as a planet comes between them and telescopes on Earth.
Space Visits
With today's tech, we are unable to detect any but the closest and largest extrasolar planets.Planets the size of Earth have too small a gravitational pull to affect their parent stars enough for astronomers to notice. Even if an Earth-sized planet passed in front of its star, the drop in brightness would barely be perceptible through Earth's atmosphere. NASA's planned Terrestrial Planet Finder is due to search the brightest 1,000 stars in the solar system between 2010 and 2020. It will be able to see Earth-sized planets and even be able to detect what their atmospheres are like.
Other Earths
In 1600, an astronomer named Giordano Bruno was burned at the stake as punishment for heresy. His crime was to suggest that around each star there may very well be planets like Earth, each with a Jesus like figure. We now know for sure that there are potentially billions of extrasolar planets in our galaxy alone, but none discovered so far have resembled Earth. In fact, the solar systems found are shockingly different to our own, formed mainly of giant planets. Orbiting Tau Bootis is a planet four times bigger than Jupiter.It is so closer to its parent star that astronomers think that its cloud may be formed from vapourized rock.
Some important facts
1) Most planets that astronomers have found so far are big as Jupiter or even bigger. Most are also very close to their parent star and are very hot.
2) Most of the extrasolar planets found to date have highly elliptical orbits that take them very close to their suns, then very far away. This means water could not remain in liquid form.
Facts and figures
First extrasolar planets discovered :
Parent star : Mass of planet
51 Pegasi 150 x Earth
55 Cancri 270 x Earth
47 Ursae Majoris 890 x Earth
Tau Bootes 1,230 x Earth
Upsilon Andromedae 220 x Earth
70 Virginis 2,100 x Earth
16 Cygni B 480 x Earth
Rho Coronae Borealis 350 x Earth
Gliese 876,670 x Earth
0 comments:
Speak up your mind
Tell us what you're thinking... !