A nearby solar system with seven Earth-sized planets has been discovered by astronomers, three of which have the possibility of liquid water because of their proximity to the star they're orbiting.
"These planets are exactly the right distance away that the water is not going to boil because it's too hot but they're also not so far away that water's going to freeze," Dr Simon Murphy from the University of Sydney's Institute for Astronomy said.
The star, known as TRAPPIST-1, is a small, dim celestial body in the constellation Aquarius, with the seven planets passing around it once every two to nine days.
“We know that they are similar in mass and size to earth so we hypothesise from that that they’re similar in composition to the earth.”
The system is located nearly 40 light years away from Earth but because of the proximity of the system, and large size of the planets, questions have been raised about the possibility of life.
“Finding water on other worlds is part of that story to the possibility of life in the universe,” Glen Nagle from the CSIRO NASA Tracking Station told SBS.
“Now we want to have a closer look using new instruments coming along in the next few years to help us actually image these worlds and get studies of their atmospheres.”
The discovery, published in this week's issue of the journal Nature, builds on previous research showing three planets circling TRAPPIST-1. They are among more than 3500 planets discovered beyond the solar system, or exoplanets.
Researchers have focused on finding Earth-sized rocky planets with the right temperatures so that water, if any exists, would be liquid, a condition believed to be necessary for life.
The diameter of TRAPPIST-1 is about 8 per cent of the sun's size. That makes its Earth-sized planets appear large as they parade past.
From the vantage point of telescopes on Earth, the planets' motions regularly block out sections of the star's light. Scientists determined the system's architecture by studying these dips.
"The data is really clear and unambiguous," Triaud wrote in an email to Reuters.
Even if the planets do not have life now, it could evolve. TRAPPIST-1 is at least 500 million years old, but has an estimated lifespan of 10 trillion years. The sun, by comparison, is about halfway through its estimated 10-billion-year life.
In a few billion years, when the sun has run out of fuel and the solar system has ceased to exist, TRAPPIST-1 will still be an infant star, astronomer Ignas Snellen, with the Netherlands' Leiden Observatory, wrote in a related essay in Nature.
Unfortunately, heading to the new solar system won’t be quick and would take more than 700,000 years using the space technology in existence.
“Maybe we should set our sights on getting astronauts onto Mars first which at closest approach is about one-third the distance between Earth and the sun,” Dr Simon Murphy said.
-With AAP
