Ôn tập unit 4 ourworld

Two planets in our universe / solar system orbit the sun closer than Earth.

• universe

• solar system

A comet / planet may need an atmosphere to support life.

• comet

• planet

We use radios to communicate / journey with spacecraft.

• communicate

• journey

We use radios to communicate / journey with spacecraft.

• communicate

• journey

Scientists collect search / data to look for life on other planets.

• data

• search

Astronauts use a spacecraft to get to the rocket / space station

• rocket

• space station

We have sent astronauts / extraterrestrials into space.

• astronauts

• extraterrestrials

Scientists use SETI to search / debate for extraterrestrial intelligence.

• search

• debate

Some spacecraft / comets have big orbits that go outside of the solar system.

• spacecraft

• comets

Two moons __________ the planet Mars.

• debate

• orbit

• search