Exoplanets: Crash Course Astronomy #27

What type of celestial body were the first confirmed exoplanets found to be orbiting?

• A sun-like star.

• A black hole.

• A pulsar.

• A red giant.

How do astronomers indirectly detect exoplanets orbiting distant stars?

• By directly observing the planet's light through powerful telescopes.

• By measuring the slight wobble of the star caused by the planet's gravitational pull.

• By detecting radio signals emitted by the exoplanet.

• By observing changes in the star's brightness as the planet passes in front of it.

Which of the following characteristics describes the exoplanet 51 Pegasi b?

• It has an orbital period of several years and is smaller than Earth.

• It is a gas giant with a very short orbital period, orbiting extremely close to its star.

• It is a rocky planet with a thick atmosphere, similar to Venus.

• It orbits its star at a distance similar to Mercury in our solar system.

What is the accepted explanation for why "Hot Jupiters" orbit so close to their parent stars?

• They formed in their current close orbits, defying traditional planetary formation models.

• They were ejected from other star systems and captured by their current star.

• They formed farther away from the star and then migrated inward.

• They are remnants of stars that have lost most of their mass.

What phenomenon occurs when a planet passes directly in front of its star from an observer's perspective?

• Doppler shift

• Gravitational lensing

• Transit

• Stellar flare

What two properties of an exoplanet can be determined by combining observations of starlight blocked during a transit and the star's Doppler shift?

• Temperature and atmospheric composition

• Orbital period and magnetic field strength

• Size and density

• Age and surface gravity

What was the primary mission of the Kepler space telescope launched by NASA in 2009?

• To photograph distant galaxies

• To study the composition of asteroids

• To detect exoplanet transits by observing changes in star brightness

• To map the cosmic microwave background radiation

Based on current extrapolations, approximately how many Earth-like planets might exist in our galaxy?

• Thousands

• Millions

• Billions

• Trillions