A solar system of seven planets, including three “goldilocks” planets, has been discovered NASA announced today. The planets orbit Trappist I, a small, ultra-cool dwarf star 39 light-years from Earth.
The three habitable planets orbit closely and quickly around Trappist I due to the star’s small mass and light gravitational pull. But because the star is so much cooler than our sun, the planets circling close to it don’t get too hot. Their atmospheric temperatures are “just right” for life.
All three of the planets in “the habitable zone” are similar in size to Earth, and are rocky planets, not mostly gas. The “goldilocks” planets are shown in the illustration to the right as planets e, f and g.
To collect the data on this extraordinary solar system, The Spitzer Space Telescope was put into service. Spitzer precisely measured the brightness of Trappist I and observed tiny fluctuations in the amount of light it emitted. By analyzing those fluctuations it was determined planets were passing in front of the star, causing it’s light to dim slightly.
Astronomers estimated the size of each planet by measuring how much the light diminished. Then, by measuring the length of the changes in brightness, they could determine the period of each planet’s orbit.
The gravitational pull exerted by the planets on each other causes small variations in their orbits. Using this information, astronomers estimated each planet’s mass. Additionally, The Hubble Space Telescope found low levels of hydrogen and helium in their atmospheres. These findings helped determined all three “goldilocks” planets to be rocky.
One of the most exciting possibilities is the presence of liquid water on each of the three planets, astronomers said.
Astronomers described the three planets being close enough to each another that they appear like large, nearby moons, not faint flickers of light.
Next year, the launch of the James Webb Space Telescope will bring important new data about the planets. The telescope will look for greenhouse gases: O2, ozone and methane, which are signs of the existence of life.