What You Need to Know

Key Concept Diagram

Satellites orbit Earth using the balance between gravitational pull and orbital velocity

Communication, GPS, weather forecasting, and remote sensing all depend on satellites

Telescopes detecting different wavelengths (radio, infrared, X-ray) reveal aspects of the universe invisible to optical telescopes

Space probes such as Voyager and New Horizons have extended humanity's direct observations beyond the solar system

The International Space Station conducts experiments in microgravity, advancing medicine and materials science

Key Vocabulary

Orbital velocity

The speed required for an object to maintain a stable orbit around a body such as Earth

Remote sensing

The use of satellites to collect data about Earth's surface and atmosphere from a distance

Electromagnetic spectrum

The full range of electromagnetic radiation from radio waves to gamma rays, including visible light

Microgravity

The condition of apparent weightlessness experienced in orbit, where gravitational effects are greatly reduced

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

What keeps a satellite in a stable orbit around Earth?

A rocket continuously firing Magnetic attraction from Earth's core The satellite being weightless The balance between gravitational pull and the satellite's orbital velocity

Question 2

Why do astronomers use X-ray and radio telescopes in addition to optical telescopes?

Different wavelengths reveal different objects and phenomena invisible to ordinary light Optical telescopes are banned in space They are cheaper to build X-ray and radio telescopes work in daylight but optical ones do not

Question 3

What scientific advantage does conducting experiments on the International Space Station provide?

Experiments are conducted faster in orbit The microgravity environment allows study of processes impossible to isolate on Earth The ISS has more powerful computers than any on Earth Astronauts can observe the Sun more closely

Space Technology and Exploration