Observing planets of other stars: the obstacles are tremendous. We measure those distances in trillions of miles, thousands of times farther than the limit of the unaided human eye on Earth (somewhere around the orbit of planet 7, Uranus).
Another challenge is the glare created by these stars. Imagine the bright headlights of a car in your rearview. Do you think your eyes would pick up the glow of a driver’s cigarette? JPL scientists think they have a method to ferret out the glare of stars and visually detect a planet about the size of the Earth.
At present, most planets beyond our solar system are detected indirectly. The most common method is to measure the gravitational tug of the planet on the star and how that affects radiant energy reaching the Earth. Scientists detect mostly “hot Jupiters,” (Jupiter-sized planets as close or closer than Mercury is to the sun) because the planets are large enough and close enough to discern a regular pattern in the shifting of the light that reaches Earth.
Recently, scientists have found that when a planet passes between its home star and the Earth, a small drop in total light can just be detected. However, only a small percentage of planets are lucky enough to have orbits aligned just right for our viewing.
Exoplanetologists are no doubt excited to be closer to pointing to a teeny blot of light and saying, “There’s my planet!”