In recent years, 11 planets tens of light-years from Earth have been located using modern techniques. Now the scientists are trying to guess what they look like and if there is a chance for life on them
"Every new observation can change old theories, that's the beauty of science," says Akiva Bar-Nun, professor of planetary sciences at Tel Aviv University, explaining the excitement surrounding the discovery of new planets outside the solar system. In 1995, a planet was discovered orbiting the star 51 Pegasi, and since then the discoveries of 11 other planets have been confirmed; It was only in June of this year that astronomers announced the discovery of six planets, the mass of each of which is similar to that of Jupiter. They move in elliptical orbits, each around a different sun.
The astronomers say that the burst of discoveries stems from the development of the spectrometer - a device that breaks the light of the stars into their color components and enables a detailed analysis of their composition - as well as from the development of computer programs that help detect very slight changes in the wavelength of the light of stars, which indicate planets orbiting them.
The planet has no light of its own, and its mass is also relatively small, so we do not see it but only the effect of its rotation on the light coming from the main star, that is, the sun of that system. From this data the scientists can deduce the mass of the planet and its distance from the main star.
The detection techniques still do not allow a sufficient level of sensitivity to detect planets whose mass is less than that of Jupiter. But the astronomers hope that before long we will be able to see if there are also Earth-like worlds (at least in terms of their size) in the solar systems where the large planets were discovered. In 2001, NASA plans to launch a satellite with measuring instruments that will be able to discover up to 2,400 moon planets; The researchers estimate that about a hundred of them will be the size of the Earth.
The British popular science magazine "Focus" states that one of the stars with a chance of finding Earth-like planets nearby is a warm white dwarf located 16 light-years from Earth and named 40 Iridani (I wonder how much the magazine's determination is influenced by the fact that in the science fiction series "Star Trek" orbits the 40 Iridani the planet Vulcan).
The discovered planets move in such unusual orbits and the data collected on them are so strange that it seems that all the old theories about the formation of planets must be thrown out. Prof. Bar-Nun: "Until the discovery of these planets, we thought we understood how the solar system was formed. In our solar system, all the minor planets are close to the sun, and they contain mostly rock and iron. When we move out to the edge of the solar system, we find gas giants, especially Jupiter and Saturn, which have a mass a thousand times greater than the mass of the Earth, and this is because they collected all the gases that were around when the Solar System was formed, while the Earth, for example, collected only rocks and minerals".
According to him, scientists have so far tended to explain this phenomenon by saying that the low temperatures in stars far from the Sun caused liquids to freeze and as a result a large amount of solid matter was formed at once. "This amount also attracted the gases, mainly hydrogen," he says. As is the way of science, when there is a series of data an explanation is given according to it. Suddenly a planet the size of Jupiter is discovered, very close to the central star of its system. if he
So close, how can it be so big, Bar-Nun asks. "Then we start to twist.
One of the possibilities, and this was discussed at the conference I attended, is that the star may have formed far away and then drifted inward, towards the central star."
The following descriptions of distant planets are taken from the October issue of Focus. They were formulated according to information accumulated about the type of sun, the distance between it and the planet in question and the size of the planet.
The first planet discovered is known as "51 Pegasi B". It is a gas giant, whose mass is about 60% that of Jupiter. This world is mostly reminiscent of hell. The star is 42 light years away from us, but only 8 million km from its sun (for comparison, Earth is 150 million km from the sun). Proximity creates strong tidal waves in a four day cycle. 51 Pegasi B Mirror to his sun - 51 Pegasi - only one side all the time. This side is exposed to a powerful stream of energy-charged particles that causes great destruction.
But the calculations show that despite these energy blows, the planet may, thanks to its size, contain an atmosphere, even if a hostile atmosphere. The temperature is estimated at about 1,200 degrees Celsius. The surface facing the sun is covered with magnetic storm clouds, which emit hot gas like the gas emitted from volcanoes. A rain of molten metal falls all the time. The other side of the star, far from the sun, is no more welcoming. Silver-white clouds rain ammonia ice crystals, and massive lightning storms rage.
This is a world that receives enormous energy from the outside and burns it from the inside. The energy created by the tidal waves heats the star from the inside. Beneath the surface, the ground is burning, made of rocks of molten magma, magma erupting from huge volcanoes.
The mass of "70 Virginis B", which is 78 light years from Earth, is 6.4 times that of Jupiter. This planet orbits the star 70 Virginis, which is twice the diameter of our Sun but has a similar mass to that of the Sun. While 2 Virginis B appears inhospitable to life, the temperature on each of its moons—if any—may be
Allows flowing water, and theoretically also life. Scientists predict two types of moons to orbit this planet. One type is inner moons, which lie below the planet's protective radiation belt and are baked by the heat generated by tidal forces. These stars appear to be more similar to our Moon or Mercury than to a life-bearing planet. But it is possible that there is also another type of moons, more distant, with a thin layer of atmosphere and a self-magnetic field that protects them. These stars may be life-bearing.
The planet "35 Kansari B" is 44 light years from Earth, and its mass is 80% that of Jupiter. It is so close to its sun that it takes only 14.8 days to orbit. The heat in it is enormous. It can be described as a kind of hybrid between Jupiter and Venus. The scientists believe that it has strong volcanic activity. They cannot tell whether its surface is solid or molten.
The volcanoes, whose activity is accelerated due to the tidal waves created due to the great proximity to the sun, emit large amounts of carbon dioxide, water vapor, and sulfur dioxide into the atmosphere. The greenhouse gases prevent the heat from escaping into space. Huge lightning bolts from sulfur clouds strike the star, lighting up the sky of the dark side. The size of the clouds is the size of the entire earth, and below them the volcanoes throw molten rocks to a distance of
thousands of kilometers. If the 35 Kansari B's have moons, they are as bald as Mercury, and as hostile as the planet they orbit.
