Australian Science Illustrated — Issue 54 2017

BC?

32 | SCIENCE ILLUSTRATED

ROBOTIC TELESCOPE

SPOTS TWO ROCKY PLANETS

1

In 2016, the Trappist robotic telescope,

which is looking for close stars from

the La Silla Observatory in Chile,

discovered the two innermost planets orbiting

the red dwarf star 39 light years from Earth. At

that time, astronomers estimated that the star

might include another planet orbiting further

away from the star.

SPACE TELESCOPE

ZOOMS IN ON THE SYSTEM

2

The telescope observes planets in

visible and near-infrared light, but red

dwarfs particularly emit infrared heat

radiation. So, astronomers aimed the Spitzer

space telescope at the star. Spitzer observes

infrared light and can more easily detect the

light reduction, as a planet passes in front of

the dwarf star.

20 DAYS OF OBSERVATIONS

REVEAL FIVE EXTRA PLANETS

3

The Spitzer space telescope observed

the dwarf star for 20 consecutive days,

capturing a total of 34 infrared light

reductions, which were due to the passage of

seven different planets. The extent of the light

reductions and the period between passages

reveal the planets' sizes and orbits, based on

which masses can be found.

A shallow ocean with small

islands. That might be what

the surface of the Trappist-1f

rocky planet looks like.

34 light reductions revealed planets

A small telescope discovered the two innermost planets orbiting Trappist-1. But when the

Spitzer telescope took a look at the star, the last five Earth-like planets became visible.

JPL-CALTECH/NASA

TRAPPIST-1 STAR-

LIGHT

PLANET PASSAGE

PLANET

PLANET

SPACE EXOPLANETS