Exoplanet discovery: What does Nasa's announcement mean- and should we be excited about TRAPPIST-1?
Turns out it wasn’t just dust on the telescope lens, Nasa astronomers have spotted seven Earth-size planets around a nearby star, some or all of which could harbour water and possibly life.
Google has marked the Earth-shattering discovery with a Doodle, featuring the seven planets squeezing into view on the earth's telescope.
What is TRAPPIST-1?
TRAPPIST-1 stands for Transiting Planets and Planetesimals Small Telescope. The discovery is a small, dim star in the constellation Aquarius, less than 40 light-years from Earth, or 235 trillion miles away, according to Nasa and the Belgian-led research team who announced its discovery on Wednesday.
Seven planets circle Trappist-1, with orbits ranging from one and a half to 20 days. If Trappist-1 were our sun, all these planets would fit inside the orbit of Mercury. That's how close they are to their star and why their orbits are so short. The planets have no real names. They're only known by letters, "b" through "h." The letter "A" refers to the star itself.
Can this newly discovered solar system support life?
Six of TRAPPIST-1's "exoplanets" lie in a temperate zone where surface temperatures range from zero to 100C.
Of these, at least three are thought to be capable of having watery oceans, greatly increasing the likelihood of life.
No other star system known contains such a large number of Earth-sized and probably rocky planets.
All are about the same size as Earth or Venus, or slightly smaller. Because the parent star is so dim, the planets are warmed gently despite having orbits much smaller than that of Mercury, the planet closest to the sun.
Scientists said they need to study the atmospheres before determining whether these rocky, terrestrial planets could support some sort of life.
What do the planets and solar system look like?
As well as being in tight orbits, the TRAPPIST-1 planets are unusually close to one another, conjuring an image straight out of science fiction.
If Trappist-1 were our sun, all seven planets would be inside Mercury's orbit. Mercury is the innermost planet of our own solar system.
From the viewpoint of someone standing on the surface of one of the planets, some of the other worlds would appear larger than the moon in the Earth's sky.
Gazing up, it would be possible to see the geological features, oceans and clouds of your planetary neighbours.
The ultracool star at the heart of this system would shine 200 times dimmer than our sun, a perpetual twilight as we know it. And the star would glow red - maybe salmon-colored, the researchers speculate.
Why all the excitement?
Three of TRAPPIST-1's "exoplanets" are smack dab in the so-called habitable zone, also known as the Goldilocks zone, where conditions are just right for watery oceans - not too much and not too little stellar energy - greatly increasing the likelihood of life.
