The Super Earths
01- K-11
02- Migrating Worlds
03- Gliese 581
04- Goldilocks
05- 51 Pegasi
06- Doppler Effect
07- Rhythmic Shift
08- Eccentric Giants
09- Transitters
10- Mu Arae
11- Intermediate World
12- Worlds Observed
13- Extra Solar Earths
14- Migrant Worlds
15- Accretion
16- Core Accretion
17- Disk Erosion
18- Planetary Embryos
19- The Protected Zone
20- Ecosphere
21- Ecosphere II
22- Beta Pictoris
23- Vanquishing Starlight
24- Red Edge / Earth Shine
25- Distant Continents
26- The Age of Stars

24 - Red Edge / Earth Shine



That faint point of light, it can tell a lot about the world in question. The light we receive contains all the information about whether that distant world has an atmosphere and a surface like Earth's. Deducing these things means knowing what our own planet would look like if its light were reduced to a single point.

‘Earth-shine’ is sunlight reflected from the Earth onto the moon's surface and back again. It is a jumble of light from our atmosphere, clouds, oceans, and continents. The distant light from an alien Earth would also combine light from all of its surface features and atmosphere.

Earthshine can be unscrambled to see the imprint of gases in our atmosphere, the colour of the oceans, and the blue sky. They can even discern a signature of vegetation called the RED EDGE: a jump in the brightness and the boundary between red light - which plants absorb - and infrared, which they reflect.

TPF, The Terrestrial Planet Finder, will start a two part space mission, between 2014 and 2020, to find that distant point of light.

TPF should be able to see signs such as carbon dioxide and water vapour.

  Alan Lambert 2011