P16: Space Physics

What is the structure of our solar system

The solar system consists of one star (the Sun), eight planets orbiting it, dwarf planets (like Pluto), natural satellites (moons orbiting planets), and artificial satellites.

How did the Sun form

A cloud of dust and gas called a nebula was pulled together by gravitational attraction, causing particles to collide, heat up, and form a protostar.

How does a star achieve main sequence stability

Fusion reactions release energy that creates an outward radiation pressure, which perfectly balances the inward gravitational collapse.

What is the life cycle of a main sequence star similar in size to the Sun

Nebula to protostar to main sequence star to red giant to white dwarf to cooling black dwarf.

What is the life cycle of a massive star larger than the Sun

Nebula to protostar to main sequence star to red supergiant to supernova, leaving behind either a neutron star or a black hole.

How are heavy elements produced and distributed in the universe

Elements up to iron are fused inside stars during nuclear fusion, while elements heavier than iron are created only in a supernova explosion and distributed across the universe.

How does gravity maintain circular orbits

Gravity provides the centripetal force directed towards the center of the orbit, pulling the object into a curved path without changing its speed.

Why does an orbiting object change velocity while maintaining a constant speed

Motion in a circular orbit constantly changes direction, and because velocity is a vector quantity (speed with direction), a changing direction means velocity is constantly changing (accelerating).

What is the relationship between orbital radius and orbital speed

To maintain a stable orbit at a smaller radius, an object must move faster to overcome the stronger gravitational force.

What is red-shift

The observed increase in the wavelength of light emitted from distant galaxies, shifting light towards the red end of the spectrum as they move away from Earth.

What does red-shift tell us about the expansion of the universe

Farther galaxies display greater red-shift, showing that distant galaxies are moving away faster and that space itself is expanding.

How does red-shift support the Big Bang theory

It provides evidence that the universe started from a extremely small, hot, and dense point and has been expanding outward ever since.

What are cosmic microwave background radiation and dark mass/energy

CMBR is thermal radiation left over from the Big Bang that fills the entire universe