NASA's James Webb Space Telescope launched to space on Christmas Day, a major milestone for a telescope that promises to change scientists' understanding of the history of our universe.

Why it matters: The telescope, known as the Hubble Space Telescope's successor, is designed to capture the light of some of the first galaxies that formed after the Big Bang, parse out the atmospheres of planets in other solar systems, watch stars evolve in clouds of dust and other tasks.

What's happening: The $10 billion JWST took flight from Kourou, French Guiana at 7:20am ET atop an Ariane 5 rocket.

• "James Webb begins a voyage back to the birth of the universe," NASA spokesperson Rob Navias said upon liftoff.

Context: This is a huge moment for the scientists and engineers involved in the 20-plus-year endeavor to build and design the JWST.

• The cost of the telescope ballooned over time as technical and budgetary hiccups led to years of delays that threatened to cancel the project.

What's next: Over the next few weeks — as it makes its way out to a point about 1 million miles from Earth — the telescope will start to unfurl, deploying its tennis court-sized sunshield, gold-coated mirrors and scientific instruments into the proper configuration.

• "No one has ever before unfolded a telescope in space," JWST scientist Jane Rigby told Axios before launch. "What we're doing is necessary — astronomy simply cannot advance in some key areas until we build bigger telescopes, and that means telescopes that have to unfold."
• Unlike the Hubble, the JWST won't be able to be serviced by crewed missions should anything go wrong because of its great distance from Earth.

Go deeper: NASA's next great space telescope has arrived