1. Telescopes Telescopes come in several types.
Radio telescopes detect radio waves.
Optical detect light waves.
Refracting telescopes use a convex lens to gather light.
Telescopes are cheaper than space probes, and provide longer looks, but not as detailed.

2. More on Telescopes
The Hubble Space Telescope provides a more detailed look but was expensive to launch. It costs more than a land based telescope.
Space telescopes orbit Earth but have no people on board.
Telescopes are based in buildings called observatories.
Active optics use computers to adjust a telescope’s mirrors.
Reflecting telescopes use concave mirrors to gather light.

3. Space Things
The Moon is closest to the Earth, then Mars, and the Sun is Farthest of those three from Earth.
The Sun is larger than Saturn, which is larger than the Earth, which is larger than the moon.
Any object that revolves (orbits) another object is a satellite.
Light moves at 300,000 km/sec in a vacuum. In contrast, sound CANNOT travel through a vacuum (empty space).
Because light is coming from objects trillions and trillions and trillions of miles away, looking into space is like looking back in time.

4. Space Shuttles, Probes, and Stations
Both shuttles and stations provide opportunities for research, but the shuttles were designed to be reused and fly back to Earth.
Space probes travel out into the solar system and orbit other planets, the shuttle orbits Earth.
Rockets are engines that have everything they need for burning their own fuel.
Space Shuttles, Probes, and Stations

5. Early Days in Space Sputnik was the first manmade satellite.
Yuri Gagarin was the first human in space.
Project Mercury put Americans in space (Alan Shepard was first). John Glenn was first American to orbit the Earth.
Project Gemini came next and was practice for lunar missions.
Project Apollo put the first man on the Moon, Neil Armstrong, in