Astronomy Concepts

A set of 50 flashcards covering key concepts in astronomy, focusing on the life cycle of stars, gravitational forces, and celestial mechanics.

What do the planets in our solar system orbit around?

The planets orbit around the sun.

What type of body is the sun?

The sun is a star.

What force pulled together the cloud of dust and gas to form the Sun?

Gravitational force of attraction.

What type of reactions take place at the start of a star’s life cycle?

Fusion reactions.

What phases do stars of the same or greater size than the sun undergo?

1. Protostar phase 2. Main sequence phase.

What do stars similar to the sun become at the end of their life-cycle?

A black dwarf.

What can stars much bigger than the sun become at the end of their lifecycle?

1. Neutron star 2. Black hole.

What phases do stars of similar size to the sun undergo between being a main sequence star and a black dwarf?

1. Red giant 2. White dwarf.

What phases do stars greater in size than the sun go through between being a main sequence star and a neutron star or black hole?

1. Red super giant 2. Supernova.

What type of nuclei fuse together to form heavier elements in a star?

Hydrogen nuclei fuse to form heavier elements.

What provides the gravitational force that allows planets to maintain circular orbits?

Gravity provides the centripetal force.

Why must the radius of orbit change if the speed changes for a stable orbit?

At higher speeds, a greater centripetal force is required, achieved by reducing the radius.

How does the force of gravity acting on a satellite affect its speed and velocity?

It alters velocity since the direction is continually changing but does not change speed.

What phase follows the protostar phase in a star’s life cycle?

Main sequence phase.

At what stage of a star’s life do fusion reactions primarily occur?

During the main sequence phase.

What do stars similar to the sun eventually become after the red giant phase?

A white dwarf.

What is the final evolutionary stage of stars much larger than the sun?

Black hole.

What term describes a large star before a supernova occurs?

Red super giant.

What phase marks the explosion of a large star?

Supernova.

What type of force acts as centripetal force for a planet’s orbit?

Gravitational force.

What happens to the speed of a satellite if the gravitational force acting on it increases?

The speed of the satellite increases.

What must happen to the gravitational force in a stable orbit if the radius of the orbit decreases?

The gravitational force must increase.

What happens to stars of greater size than the sun after going through the main sequence phase?

They undergo the red super giant and supernova phases.

What does a red giant eventually become?

A white dwarf.

What allows for the formation of heavier elements within a star?

Nuclear fusion of lighter elements.

What is a black dwarf?

The final stage of a star similar to the sun after its white dwarf phase.

Which phase comes after a neutron star?

No phase – it can be a stable neutron star or collapse into a black hole.

What are the remnants of a supernova in terms of stellar evolution?

They can become either neutron stars or black holes.

What occurs during the main sequence phase of a star?

Hydrogen is fused into helium.

Where does the sun reside in the life cycle of stars?

In the main sequence phase.

What happens to the orbits of planets if there is a change in mass of the sun?

The orbits would change due to alterations in gravitational forces.

What is the relationship between the radius of a stable orbit and the speed of the orbiting object?

They are inversely related.

What happens to the gravitational pull as distance increases?

Gravitational pull decreases.

What is essential for maintaining a circular orbit?

A constant gravitational force acting as centripetal force.

How does gravitational force affect the trajectory of an orbiting object?

It continually changes the object's direction.

During which life cycle phase do stars predominantly fuse hydrogen into helium?

Main sequence phase.

What is the consequence of high speeds on the radius of orbit?

The radius must decrease to maintain circular motion.

What are the stages of stellar evolution following the main sequence phase for a high mass star?

Red super giant, supernova, either neutron star or black hole.

What is the result of a supernova explosion?

It ejects material into space and can leave behind a neutron star or black hole.