Skywatchers in the eastern United States have an opportunity to spot the launch of the SpaceX Falcon 9 rocket on an International Space Station resupply flight on Sundaynight (Oct. 7), weather permitting.

The night launch will mark the fourth flight of SpaceX's Falcon 9 rocket, a privately built boosterthat has made three successful flights since 2010. The rocket will be carrying the gumdrop-shaped Dragon capsule to the International Space Station. In May the Dragon capsule became the first U.S. spacecraft to reach the space station since NASA's last space shuttle flight departed in July 2011.

To reach the space station,the Falcon 9 rocket must be launched when Earth's rotation carries the launch pad into the plane of the station's orbit. That will happen on Sunday at 8:35 p.m. EDT (0035 Monday GMT) at Launch Complex 40, SpaceX's launch pad at the Cape Canaveral Air Force Station in Florida.

As has been the case with space shuttle launches to the space station, Sunday's liftoff will bring the Falcon 9 rocket's path nearly parallel to the U.S. East Coast. It is expected that the glow created by the rocket's Merlin 1C liquid propellant rocket engines should be visible in varying degrees along much of the Eastern seaboard. [SpaceX's Dragon Poised to Sunday Launch (Photos)]

The Falcon 9 rocket launches into orbit using two stages. The first stage utilizes nine Merlin 1C engines which will burn for three minutes, then shuts down. Five seconds later the first and second stages will separate.

Seven seconds later the second stage, which utilizes just one engine will be fired and will burn for six minutes and two seconds. The Dragon space capsule will then separate from the second stage and head into orbit.

So while the first stage should create a fairly conspicuous bright light in the sky, the second stage will likely be considerably dimmer.

Kevin Fetter, a well-known amateur satellite observer based in Canada, notes:

"The first stage from what I seeis very bright sourceof light.The second stage won't be as good for causing a light show. So once the first stage is done, the nice light show is over. The light coming from the second stage won't be as bright, so not everyone will have a nice view."

What to expect

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Private SpaceX Rocket Launch Tonight Visible from US East Coast