Meg Urry is the Israel Munson Professor of Physics and Astronomy at Yale University and recent president of the American Astronomical Society. The opinions expressed in this commentary are hers. View more opinion on CNN.

(CNN) On Saturday, SpaceX launched the unmanned Crew Dragon capsule on a Falcon 9 rocket. A little more than 24 hours later, the Crew Dragon docked successfully with the International Space Station. SpaceX CEO Elon Musk and his team are right to celebrate this tremendous achievement.

Although the relative motions are slow, the ISS zips along at about 5 miles every second, or approximately 18,000 mph. To dock with the ISS, Crew Dragon had to reach the same speed in exactly the same orbit -- no easy feat -- and to line up precisely with the docking port, approaching slowly enough (in relative terms) to not damage either vehicle.

This kind of thing is both very difficult and surprisingly old hat.

Meg Urry

The ability to dock two spacecraft was first demonstrated over 50 years ago, when the Gemini 8 crew connected with an unmanned target vehicle in 1966. The Russians caught up a year and a half later, when they successfully mated two Cosmos spacecraft.

Then as now, the Russians and United States were leaders in space. What's different about the SpaceX docking feat is that it's a private company, not a government, that's in charge of the operation.

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