Rocky, earthlike planets are way too small and dim to detect directly with today’s telescopes. Astronomers at Goddard Space Flight Center may have found a really clever way around this problem.
The NASA researchers think we might be able to spot tiny planets based on their gravitational effects on interplanetary dust particles. Our solar system has dust, and you can see it as a faint glow called the zodiacal light, visible before sunrise or after sunset.
NASA researchers led by Christopher Stark at the University of Maryland, College Park, created a computer model of 25,000 dust particles orbiting a Sun-like star and interacting gravitationally with planets from nearly the size of Mars to 5 times Earth’s diameter. The simulation also varied the size of the dust particles and the planet's distance from the central star.
As the dust and planet orbit the star, gravitational interactions between them (called resonances) create two regions — leading and trailing the planet — where thicker dust scatters starlight toward us. This brief flash could someday serve like a lighthouse beacon directing telescopes to an earthlike world.
You can see the resonances in a short video of the computer simulation. It shows a planet twice Earth’s mass shepherding nearby dust into a ring structure. The planet and dust ring orbit once every 5.2 years, although the simulation speeds up the journey.
Stark and his colleagues published their results in the October 10 issue of The Astrophysical Journal.