WALLOPS ISLAND, Va. —An Orbital ATK Antares rocket will launch a Cygnus supply ship Monday morning (May 21) to deliver more than 3 tons NASA cargo to the International Space Station, and you can watch it live online.

The Antares rocket is scheduled to lift off at 4:39 a.m. EDT (0839 GMT) from Pad-0A of the Mid-Atlantic Regional Spaceport here at NASA's Wallops Flight Facility in Virginia to the International Space Station. You can watch the launch live on Space.com, courtesy of NASA TV, beginning at 4 a.m. EDT (0800 GMT). There is a 65-percent chance of good weather at launch time, NASA officials said. Cloud cover, which may interfere with launch visibility, is the main concern, they added.

If the weather holds up on Monday, spectators on the U.S. East Coast may be able to see the rocket launchfrom all over the east coast. But our skywatching columnist Joe Rao advises people to make sure to wait a few extra minutes after liftoff for the chance to see something special. [Visibility Guide: How to See the Antares Rocket Launch Monday]

According to Rao, while the rocket's first stage might look like a shooting star or fast-moving light flying low in the sky, its second stage could appear a bit flashier, with a smoky contrail tail behind it illuminated by the sun so that it looks almost like a comet. That second-stage ignition will occur 4 minutes and 22 seconds after liftoff. The launch is scheduled for very early in the morning, but the view will be well worth the exhaustion, he advised.

This Orbital ATK map shows the visibility range along the U.S. East Coast for the May 21, 2018 launch of an Antares rocket carrying NASA cargo. The number of seconds listed refer to the time after liftoff, which is set for 4:39 a.m. EDT on May 21. (Image credit: Orbital ATK)

(Editor's note: If you spot the Antares rocket's predawn launch and snap a great photo or video, let us know! Send images and comments in to spacephotos@space.com.)

Monday's launch was originally scheduled for Sunday (May 20), but Orbital ATK and NASA postponed it to "support further pre-launch inspections and more favorable weather conditions," according to Orbital ATK representatives.

An Orbital ATK Antares rocket and the OA-9 Cygnus cargo ship are raised at their launchpad in this time-lapse view taken on May 18, 2018 for a May 21 launch from NASA's Wallops Flight Facility on Wallops Island, Virginia. (Image credit: Patrick Black/NASA)

This flight will be Orbital ATK's ninth commercial cargo flight to the space station, following OA-8 which launched last November. As part of the OA-9 mission, the Cygnus spacecraft will be carrying 7,385 lbs. (3,350 kilograms) of cargo for the Expedition 55 space station crew. In addition to supplies like clothing and food, the craft will also contain scientific equipment for a number of science experiments and demonstrations that are planned to take place aboard the space station.

The scientific equipment that Cygnus will carry to the space station ranges from packets of concrete and alcohol to traditional, metal sextants. The craft will even carry equipment from the Cold Atom Laboratory (CAL) that will create the coldest, human-made spot in the universe.

Visit Space.com Monday for complete coverage of Orbital ATK's OA-9 Cygnus launch for NASA.

Email Chelsea Gohd at cgohd@space.com or follow her @chelsea_gohd.Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.