Small changes in the movement of Neptune led several astronomers to believe that an undiscovered planet was affecting Neptune's orbit.

VOA: special.2010.07.11

Glenn's flight plan called for him to spend most of the first orbit getting used to the feeling of being weightless.

VOA: special.2009.06.17

The radio waves are measured when the earth is at two points opposite one another in its orbit.

VOA: special.2009.01.20

Military officials immediately offered to use the Jupiter to put a scientific satellite into orbit around the Earth.

VOA: special.2009.06.10

Near the moon, the astronauts fired rockets to slow the spacecraft enough to put it into moon orbit.

VOA: special.2009.07.15

Knowing more about how the Yarkovsky effect changes an asteroid's orbit will help scientists better predict whether RQ36 will come near Earth.

VOA: special.2011.06.22

Next year, the Chinese plan to launch a small space laboratory to practice docking of spacecraft in orbit.

VOA: special.2010.04.28

Gemini Six followed Gemini Seven, but in a lower orbit that moved the two spacecraft closer together.

VOA: special.2009.07.01

The twenty-two meter long rocket would put a little scientific satellite into orbit as one of the events of the international geophysical year.

VOA: special.2009.06.10

Iran launched its first satellite into orbit in February -- the thirtieth anniversary of the Islamic revolution.

VOA: special.2009.05.23

He says there are more than three hundred thousand small objects or pieces of debris in orbit that are larger than one centimeter.

VOA: special.2009.04.01

He would wait in orbit around the moon while Armstrong and Aldrin landed and explored the surface.

VOA: special.2009.07.15

Because of the gravity on Mars, spacesuits may have to be designed to be lighter than suits used in orbit or on the moon.

VOA: special.2011.04.06

The next Royal Astronomer, Edmund Halley, spent another forty years gathering information about the moon's orbit.

VOA: special.2010.07.14