Hunting for Earth 2.0: Terrestrial Exoplanets Quiz

Silicate rocks and metals is the correct answer. Terrestrial planets are defined by having a solid surface and a dense metallic core, much like Mercury, Venus, Earth, and Mars.

False. Terrestrial planets are the smallest class of planets. Even a "Super-Earth" is much smaller than a gas giant or an ice giant.

Habitable is the correct answer. Also known as the "Goldilocks Zone," this region is at the perfect distance from a star—neither too hot nor too cold—for liquid water to pool on the surface.

Earth, Mars, and Venus are the correct answers. Mercury is the fourth. Jupiter is a gas giant and does not have a solid rocky surface.

They are smaller and block less starlight is the correct answer. Because rocky planets are tiny compared to their stars, the "dip" in light they cause during a transit is extremely small and hard to measure.

False. "Terrestrial" refers to a planet's rocky composition and solid surface. While a magnetic field helps with habitability, it is not a requirement for the planet to be classified as rocky.

Super-Earth is the correct answer. This classification is based on mass (typically 1 to 10 times Earth). These worlds are significant because they represent a type of planet not found in our own solar system.

Transmission Spectroscopy is the correct answer. By analyzing starlight as it passes through the planet's atmosphere, scientists can see which colors are absorbed, telling them which gases are present.

Oxygen and Methane are the correct answers. On Earth, these gases are constantly replenished by living organisms. Carbon dioxide can come from volcanoes, so it isn't a definitive sign of life.

One side always faces the star is the correct answer. This is common for rocky planets orbiting close to Red Dwarf stars. One side is in permanent, roasting daylight, while the other is in permanent, freezing night.

True. "Lava Worlds" are rocky planets that orbit so close to their stars that their entire surface is melted into a glowing magma ocean.

Core is the correct answer. The size and state (liquid or solid) of the core determines if the planet has a magnetic field and volcanic activity.

High-energy solar flares is the correct answer. Red Dwarfs are very active and can blast nearby rocky planets with radiation, potentially stripping away their atmospheres over time.

Rocky, Habitable Zone, and Atmosphere are the correct answers. While many planets are rocky, they must also have the right temperature and air to truly be considered "Earth-like."

True. Venus is rocky and almost the same size as Earth, but its runaway greenhouse effect makes its surface hot enough to melt lead, proving that being "terrestrial" isn't enough for life.

Crust is the correct answer. This is the thin, solid shell where mountains, valleys, and (potentially) life exist.

Metal/Iron is the correct answer. Density tells us how much mass is packed into a space. High density usually means the planet has a very large iron core relative to its rocky mantle.

Seeing through dust, analyzing atmospheres, and detecting water are the correct answers. JWST is the first telescope powerful enough to study the air of rocky planets around other stars in detail.

Red Dwarfs is the correct answer. Because these stars are small and dim, it is easier for our telescopes to see the tiny dip in light caused by a small rocky planet.

False. While we have found many "Earth-sized" and "potentially habitable" planets, we don't yet have enough data to prove any of them are exactly like Earth in every way.