"I've done a lot of time-dilated travel." This statement encapsulates the essence of Grace's journey, highlighting the profound effects of traveling at speeds approaching light, where time for the traveler slows down significantly compared to those remaining on Earth.
This system is truly extraordinary. We're seeing the radio equivalent of a laser halfway across the universe. Fundamentally, masers and lasers are focused beams of light in the same frequency. In the realm of astrophysics, these can arise from clouds of dust being excited into a higher energy state from the light emitted by other sources, like stars and black holes.
In the silent vacuum of space, five autonomous robots churn through the lunar surface, digging up a loose layer of rock and dust and leaving rows of uniform tracks in their wake. Stopping only to recharge at a central solar power station, the car-sized machines process the lunar dirt internally to extract a type of helium so rare on Earth that a palm-sized container is estimated to be worth millions.
Looking skyward fills us with wonder. Off-world, the Sun, planets, stars, and galaxies all await. Our Solar System encompasses our own cosmic backyard. Farther away, stars and star clusters abound within the Milky Way. Hundreds of billions of stars exist just within our home galaxy. Inside our Local Group, only Andromeda surpasses us in mass, size, and stars. More than 5 million light-years away, galaxies abound in groups and clusters.