Object: the star HIP 56948
Size: same as the sun
Temperature: same as the sun
Composition: same as the sun
Planets: same as the sun?

On an alien world remarkably like Earth, a sun rises. Its tiny disk scours the landscape with harsh, blue-tinted light... wait a minute, that's not right. On an alien world remarkably like Earth, a sun rises. Its vast face floods the landscape with an eerie blood red glow. No no – this is still no place like home.

In the search for other Earths, the main goal is to find a planet the same size as ours that sits in the habitable zone – the region around a given star where planetary surface temperature would be similar to ours, allowing liquid water to exist. Almost all stars have such a zone. Around a hot bright star it is further out than Earth's own orbit; with a dim star it is further in.

But while an Earth-sized world in one of these habitable zones might have seas and rivers, it would look quite different bathed in blue-white or red light. That could affect the development of life. To exploit the available light, plant leaves could be yellow, orange or red, according to research in 2007 by the Virtual Planetary Laboratory at the California Institute of Technology.

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