Question

how earth discovered ?

Answer 1

European scientists found Ross 128 b using HARPS, the High Accuracy Radial velocity Planet Searcher. HARPS, which is attached to a 3.6-meter telescope at Chile's La Silla Observatory, works by splitting starlight into its component wavelengths. Exoplanets tug on their stars as they orbit, giving the stars a slight wobble. Those wobbles shift stars' spectrums, and by tracking these shifts, HARPS can infer planets are present. In this case, it took a decade of HARPS data to detect Ross 128 b.

At 11 light years away, Ross 128 b is already a stellar neighbor, but interestingly, it will soon drop by for a visit. The star is moving toward us, and will overtake Proxima Centauri as the closest sun to ours in about 79,000 years.