Seven worlds discovered in nearby star system

Astronomers have discovered seven Earth-sized planets orbiting a star just 40 light-years away. At least three of them could harbour oceans of water, increasing the possibility they could host life

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Discovery made by NASA’s Spitzer Space Telescope which produces heat-radiated images from celestial objects

Infrared radiation

TRAPPIST-1 system Located in Aquarius constellation

Central star Ultracool dwarf star, roughly same size as Jupiter

Earth to scale

Planets “e”, “f” and “g” orbit in Habitable Zone – meaning oceans of water could exist on surface

Orbital period: b 	c 	d 	e 	f 	g 	h

Days 		1.51 	2.42 	4.05	6.10	9.21	12.35	~20

Distance to star: Astronomical Units (AU)*
		0.011	0.015	0.021	0.028	0.037	0.045	~0.06

Planet radius: Relative to Earth
		1.09	1.06	0.77	0.92	1.04	1.13	0.76

Planet mass: Relative to Earth
		0.85	1.38	0.41	0.62	0.68	1.34 	-

Mass estimates for six inner planets suggest rocky composition like Earth, with surface temperatures between 0-100 degrees Celsius

*Equal to 150 million km – roughly distance from Earth to Sun

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Sources: Nature, NASA 

Pictures: Nature

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