13 record-breaking space discoveries of 2023

1. The most powerful light from the sun

Among the new astronomical records set in 2023 was an announcement of the highest-energy gamma ray ever seen coming from the sun, an order of magnitude more powerful than had previously been seen.

“The sun is more surprising than we knew,” Mehr Un Nisa, an astronomer at Michigan State University and one of the authors who described the discovery in Physical Review Letters, said in a statement.

Previously, NASA’s Fermi Gamma-ray Space Telescope had detected gamma-rays coming from the sun with energies up to 200 gigaelectronvolt, or GeV (200 billion electronvolts). That’s incredibly energetic, to say the least. These gamma-rays are produced when cosmic rays, which are particles from deep space moving at almost the speed of light, collide with the solar atmosphere. However, observations by the High-Altitude Cherenkov Observatory, or HAWC, in Mexico have officially trumped that. 

An image of the sun. (Image credit: NASA/SDO)

HAWC is able to detect gamma rays indirectly. When a gamma-ray photon enters Earth’s atmosphere, it’s bound to collide with an atmospheric molecule, smashing the molecule apart to form a shower of subatomic particles. These rain down on HAWC, which is a funny kind of telescope: it consists of 300 water tanks, each filled with 200 metric tons of water. The subatomic particles from the collision between a gamma ray and a molecule are moving so fast that when they enter water, they are actually moving faster than the speed of light through water (which is slightly slower than through a vacuum or through air). The subatomic particles produce a flash of light, a kind of visual equivalent of a sonic boom, called Cherenkov radiation.