Astronomers will have their best shot yet at finding exomoons 鈥� alien moons that orbit planets beyond the solar system 鈥� after efforts to look for them were picked for the next phase of observations with the James Webb Space Telescope (JWST).
Exomoons may be interesting locations to look for life, but no definitive detection of one has ever been made. JWST, which launched in 2021, is the first telescope in history capable of truly confirming their existence.
Every year, astronomers make proposals to the Space Telescope Science Institute (STScI) in the US, which runs JWST, for what the telescope should look at. This year鈥檚 selections were the most competitive ever, with a record 1931 programmes submitted. Only 253 proposals 鈥� roughly one in eight 鈥� were selected to make up part of JWST鈥檚 overall programme, called Cycle 3.
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Exomoon projects had never before been picked for JWST, but in the Cycle 3 selections announced on 29 February, they finally made the cut. The STScI chose five programmes related to exomoons, including two that would perform direct hunts for them. 鈥淚t鈥檚 still kind of a shock,鈥� says at Columbia University in New York, who leads one of the programmes. 鈥淚鈥檓 very excited.鈥�
Cassese鈥檚 programme will study orbiting a star called Kepler-167, which is about 1110 light-years from the solar system. The planet crosses the face of its star from our point of view once every 1000 days, causing a dip in light known as a transit.
The next crossing is in October, and Cassese鈥檚 team will watch it with JWST to look for evidence of one or more exomoons causing additional transits. , also at Columbia University and part of the team, says the planet is 鈥渙ur best target鈥� to look for an exomoon given its size and distance from its star.
Another programme, led by at Harvard University, will look for exomoons orbiting two planets around the red dwarf star TOI-700, about 100 light years from Earth. The two planets are Earth-sized and in the habitable zone, says Pass, which makes them 鈥減rime targets to search for moon-sized moons鈥�.
The selection of these two programmes is 鈥渁 significant milestone in the exomoon field鈥�, says at the University of Michigan. 鈥淭his marks the first cycle in which JWST has selected not just one, but two exciting proposals focused on the search for exomoons.鈥�
Three other programmes will perform more indirect studies of exomoons. One will look at , which could include exomoons. Another will study the same planet as Cassese鈥檚 team to about it. And a third will observe a ring of hot material caused by two planets colliding, which could be a way moons form.
But it is Cassese and Pass鈥檚 programs that will be of most interest to exomoon hunters, possibly giving us our first true detection of moons orbiting exoplanets. 鈥淩egardless of whether there are moons found, we鈥檒l learn something interesting about those systems,鈥� says at the Massachusetts Institute of Technology. 鈥淚鈥檓 crossing my fingers for seeing something totally revolutionary.鈥�
