The Secret Life of the Universe by Nathalie A. Cabrol

Author:Nathalie A. Cabrol
Language: eng
Format: epub
Publisher: Scribner
Published: 2024-08-13T00:00:00+00:00

DOTS IN THE NIGHT, OR HOW TO DETECT EXOPLANETS

A star wobbles ever so slightly in response to gravitational tugs when planets are present. This wobble translates into color shifting in the star’s natural spectrum, making it appear bluer or redder due to the Doppler effect. This way of tracking exoplanets is the radial velocity method. Another one is to search for shadows. That is the transit method. When a planet passes directly between its star and the observer, the star’s light dims ever so slightly, and that dip in light intensity is measurable. In other words, this is a photometric method. For instance, transits by terrestrial planets may dim a star’s light by 1/10,000, which speaks about the precision required to find these alien worlds.

The transit method involves studying the brightness changes of a star as a planet passes in front of it. Astronomers use this method to calculate a planet’s size by analyzing the brightness curve and knowing the star’s dimensions. They also measure the planet’s orbital period through the time between transits. With the period known, Kepler’s third law is applied to find the planet-star distance. From it, scientists can start modeling planetary environments.

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