Stephen Colbert will host Virgin Galactic's SpaceShipTwo Unity launch on Sunday

Editor's Note: Virgin Galactic's original launch window has been pushed to 10:30 a.m. EDT (1430 GMT) due to weather.

Richard Branson's spaceflight is shaping up to be quite a star-studded affair.

The billionaire entrepreneur is scheduled to fly to suborbital space aboard Virgin Galactic's VSS Unity SpaceShipTwo vehicle on Sunday (July 11). You can watch webcast coverage of the test mission here at Space.com courtesy of Virgin Galactic or directly via the company, beginning at 9 a.m. EDT (1300 GMT).

And you should watch, even if you're not a big space fan, because the webcast will be hosted by Stephen Colbert.

Colbert came into the duties in a somewhat slapdash fashion. On Thursday (July 8), he tweeted congratulations to Branson and joked that his invitation to the big event must have gone straight to his spam folder. Branson replied with a livestream-hosting offer, and Colbert responded, "I'm in! BLAST OFF!"

Related: How to watch Virgin Galactic launch Richard Branson to space

Colbert will be joined by the singer Khalid, who will premiere a song during the webcast; Canadian astronaut Chris Hadfield; and science communicator Kellie Gerardi, Virgin Galactic said via Twitter on Friday (July 9).

Sunday's mission, which departs from Spaceport America in New Mexico, will be Unity's fourth test flight to suborbital space. The other three occurred in December 2018, February 2019 and May of this year.

The six-passenger, two-pilot Unity takes off under the wings of a carrier aircraft known as VMS Eve. At an altitude of about 50,000 feet (15,000 meters), Eve drops Unity, which then fires up its onboard rocket motor and powers itself to suborbital space.

Unity is in the final stages of its test-flight program. If all goes well with Sunday's flight and a few more in the fall, the spaceliner will be clear to begin commercial operations early next year, Virgin Galactic representatives have said.

Virgin Galactic's chief competitor in the suborbital space tourism industry, Jeff Bezos' Blue Origin, is gearing up for a big flight of its own this month. Bezos and three other people, including pioneering aviator Wally Funk, are scheduled to launch July 20 on the first crewed flight of Blue Origin's New Shepard suborbital vehicle. No word yet on who will host that webcast.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.