Philadelphia residents looking skyward Sunday night might notice a bright plume streaking across the sky.

Don't mistake it for a shooting star, an airplane or a UFO. It's a private spacecraft being launched from the Mid-Atlantic Regional Spaceport on Wallops Island, Virginia.

The unmanned Cygnus cargo ship will be blasted to the International Space Station by a two-stage Antares rocket developed by Orbital ATK, according to NASA. The launch is slated for 8:03 p.m. Sunday, but it could get delayed by Tropical Storm Nicole.

If the skies are clear — meteorologists currently project partly cloudy skies — the rocket's plume should be visible throughout much of the Northeast, according to Space.com. It will appear in the Philadelphia skies about 90 seconds after launch.

The launch originally was slated for Friday, but forecasts for Tropical Storm Nicole caused NASA and Orbital ATK to postpone it until Sunday, at the earliest. The storm could interfere with a necessary tracking station in Bermuda. The launch trajectory sends the spacecraft on a southeastern path, away from the mainland United States.





“The ability to support a launch will depend on the impact the storm has on not only our systems, but also the overall Bermuda infrastructure," Steven Kremer, chief of the Wallops Range and Mission Management Office, said in a statement.



The launch marks the first time Orbital ATK will launch its Antares rocket since one exploded shortly after liftoff nearly two years ago.