Approaching the discovery of Earth's twin brothers

Planet hunters said it was only a matter of time before they found Earth's twin brothers. This Earth-like planet is definitely hiding somewhere in our galaxy.

Last week, astronomers announced that they had detected three super-Earths - planets larger than us and formed from rocks - orbiting a star. Dozens of such planets with the same magnitude have been found around other stars.

Alan Boss, a theorist with the Carnegie Institution of Washington, Washington, DC, said: 'The discovery of three planets about the size of the Earth around a star shows the number of planets that exist around Earth. stars are more than we thought. '

Since the early 1990s, when the first planet outside the solar system was discovered orbiting the pulsar PSR 1257, astronomers have discovered about 300 similar planets. However, most are giant gas planets called Jupiter spinning near their star, simply because they are easier to detect.

One of the planet hunters, Geoff Marcy of the University of California, Berkeley, said: 'So far we have found Jupiter and Saturn, and the current technology is so modern that it can detect traces. smaller crystals, about the same size as Uranus and Neptune, even smaller. '

Marcy, Boss and other scientists believe that within the next 5 years , newspapers will be flooded with the title of an identical planet Earth exists in another solar system.

Boss told SPACE.com: 'The amazing thing is that for thousands of years, people look up at stars, wondering if there is a similar planet Earth exists somewhere or not. Now we can say that there are certainly Earth-like planets orbiting so many stars. We can't see them, but they certainly exist. '

Search for small planets

There are two methods that have become the standard for finding other planets. Most planets are widely known, discovered by radial velocity. Astronomers observe small vibrations in the star's motion because of the gravitational pull of the planet around it. This method is effective in detecting very large and close planets.

With the method of physical movement, astronomers observe the part of the light fading when a planet passes through the front of a star. This method works when telescopes scan light from hundreds to thousands of stars at once.

Both methods are limited because of the ability of the planet to create black shadows. For example, the sun is 100 times bigger, weighing 300,000 times and being 10 billion times brighter than the Earth . 'Detecting the Earth in reflected light is like finding a firefly in a halo of 2,400 miles long , ' a group of astronomers wrote in the report of the Search for Extraterrestrial Planet.

With the upgrade of spectrophotometers and digital cameras attached to telescopes, astronomers have more sensitive devices for very small vibrations of stars (determined by step changes). waves of light) and the dim part of the light is obscured by the small planet.

The discovery of super-Earth announced last week reflects the leap forward in this technology.

David Charboneua of the Harvard-Smithsonian Center for Astrophysics in Massachusetts said: 'I think the reason astronomers are really excited [about the discovery of super-Earths] is that it shows the complete technology foundation. Therefore, they can detect microscopic vibrations caused by small mass planets. The vibrations were measured from quite large stars. If they can get the same accuracy for smaller stars, they will find smaller planets, similar to Earth. '

Illustrations of 3 super-Earths orbiting a star like the sun, HD 40307 have just been discovered.(Photo: ESO)

Follow the trail

To further leverage existing technologies, Charbonneau said astronomers should search for planets around small stars.

In fact he and his colleagues are searching for planets orbiting M stars, or red stars, more than 50% dimmer and lower mass than the Sun. Red stars are also said to be the most popular stars in the universe.

Charbonneau said: 'I think this is an opportunity to study low-mass stars, because we are looking for very small planets. The difficulty is the ratio between the mass of the planet and the mass of the star, or the size of the planet and the size of the star depending on the detection method '.

Low mass and luminosity means any change of the star created by a planet with the same mass as the Earth can be easily identified.

James Kasting, who studies the planetary atmosphere and the habitable regions of extraterrestrial planets, said: 'A M star is 10 times smaller than the Sun. So if Earth passes through the front of an M star, it will generate 1% of the signal. It is like Jupiter going through the front of the Sun. With this method we can detect a planet identical to the Earth within the next 5 to 10 years. '

Other research groups are ready for the hunt for Earth-like planets orbiting mother stars like the Sun. NASA's Kepler Observatory will be operational in February 2009. After that time, this observatory's high-power telescope will observe about 100,000 stars in the Milky Way to search for dim parts of the light. because the planet passes through the front of the star mother.

The French COROT spacecraft was launched into space with the same mission.

Find

The ultimate goal of planet hunting projects is to find the Earth's twin.

'We are looking for the twins of the Earth, a planet that has all the Earth-like characteristics , ' Marcy said in a telephone interview. He is currently searching for Super Earth at Keck Observatory, Hawaii.

Such a planet will have the same chemical composition as the Earth, and rotate around the region where the star may exist.

The possible area is the distance a planet must orbit its parent so that liquid water can exist on its surface - not as hot as Venus, not as cold as Neptune or Pluto.

Astronomers have found rotating planets quite close to the parent's likely habitat.

Marcy said: 'I think there are planets like Earth with lakes, rivers and streams, waterfalls and beautiful ice canyons'.

Extraterrestrial life

Finding a planet in a viable area is the first step towards finding life beyond Earth.

Boss said: 'When we say it's a habitable planet, that planet has the ability to hide life. To go further, search for a planet that you really can live on, you have to study the planet's atmosphere. '

The James Webb Space Telescope, launched in 2013, is for this purpose.

Earth and planetary scientist Diana Valencia of Harvard University said: 'There may be a signal in the atmosphere that shows there are tectonic plates on the planet'.

Her computer model shows that tectonic tectonics, forces moving continents and lifting giant mountain ranges, are key to life on Earth, and possibly life on other planets. The rock strata that make up the planet's outer shell release carbon dioxide. This greenhouse gas keeps the planet's temperature moderate, not too hot.A signal like smoke can show certain concentrations of carbon dioxide, and the planet, like Earth, relies on stratigraphic tectonics to regenerate carbon.

Marcy said: 'Certainly there are planets like Earth that exist, because of the number of stars and extremely large galaxies in the universe. However, there is a deeper question, are Earth-like planets popular? Do the planets like Earth have dozens, or are they quite rare, one in a thousand, or one in a million? "