How the Sun Works
The Sun’s energy is produced in this layer, where hydrogen atoms fuse to form helium.
What is the core?
Our Sun is currently in this stage of its life cycle.
What is the main sequence?
What shape are planetary orbits?
Elliptical
Why is Earth habitable?
Liquid water and moderate temps
What is an exoplanet?
Planet outside our solar system
What process powers the Sun by converting hydrogen into helium?
Nuclear fusion
A star’s lifespan depends mainly on this characteristic.
What is its mass?
When does a planet move fastest in its orbit?
When closest to the Sun
Why can’t Mercury or Venus support life?
Too hot for liquid water
What three conditions make an exoplanet more likely to be habitable?
Right distance, stable orbit, atmosphere
Why can nuclear reactions power the Sun for billions of years?
They release far more energy than chemical reactions
What is it called when a stars gravity pulling inward and fusion pressure pushing outward are balanced?
What is equilibrium?
How does a planet’s distance affect its revolution period?
Farther = longer orbit
What type of water is found on Mars, and where is most of it located?
Mostly ice, found near the poles and beneath the surface.
What two properties help classify a planet as terrestrial or gas?
Mass and density
What do absorption lines in the Sun’s spectrum show?
Its elements
High-mass stars end their lives in this powerful explosion that creates elements heavier than iron.
What is a supernova?
Of the eight planets in our solar system, which planet has the most elliptical orbit?
Mercury
Why is the presence of liquid water used as a key indicator for habitability on other planets and moons?
Because all known life on Earth depends on water for chemical reactions and stability.
How does NASA use the transit method to find exoplanets like Kepler-442b or Kepler-186f?
By measuring a star’s light dimming as a planet passes in front
Why does the Sun stay stable for billions of years?
Gravity and fusion are balanced
What elements form only in a supernova?
Heavier than iron
How does high orbital eccentricity affect habitability?
Causes big temperature swings
What evidence suggests that Europa, one of Jupiter’s moons, might have the conditions for life?
It has a subsurface ocean of salty liquid water beneath an icy crust.
How can the transit method help scientists decide if an exoplanet is in the habitable zone?
The size and timing of the dip show orbit distance and possible liquid water range