The Solar System, Stars & The Universe
Space physics examines the formation and life cycle of stars, the mechanics of planetary and satellite orbits, and cosmological evidence for the origin of the universe. Observations of galactic red-shift and cosmic microwave background radiation support the Big Bang model of an expanding universe.
- Nebula
- A massive cloud of gas (mostly hydrogen) and dust in space, from which stars are formed.
- Main Sequence Star
- A stable period in a star's life where the inward force of gravity is balanced by the outward pressure from nuclear fusion.
- Supernova
- The explosion of a massive star at the end of its life, which distributes heavy elements throughout the universe.
The Solar System, Stars & The Universe: Wave Equation (v = fλ) & Force Vector (F = ma) Simulator
Adjust physical variables on the sliders below to see real-time changes in wave geometry, resultant forces, and acceleration.
F_net = 80 N − 25 N = 55 NAcceleration: a = F_net ÷ m = 55 ÷ 10 = 5.50 m/s²Key Concepts & Exam Definitions (5)
- Nebula
- A massive cloud of gas (mostly hydrogen) and dust in space, from which stars are formed.
- Main Sequence Star
- A stable period in a star's life where the inward force of gravity is balanced by the outward pressure from nuclear fusion.
- Supernova
- The explosion of a massive star at the end of its life, which distributes heavy elements throughout the universe.
- Red-Shift
- The shifting of light from distant galaxies towards the red end of the spectrum, providing evidence that the universe is expanding.
- Black Hole
- An object in space with gravity so strong that not even light can escape from it, formed after a supernova.
Quick-Fire Flashcards (5)
Click any card to check the answer, then mark it as Known to track your progress.
What process powers the Sun?
What does a main sequence star like the Sun become next?
What is the final stage of the Sun's life cycle?
What provides evidence that the universe is expanding?
What force causes a nebula to collapse and form a protostar?
Exam-Style Questions & Mark Schemes (3)
Write or think through your answer first, then click Check Mark Scheme to see the exact points examiners award marks for.
- Q1
Describe the life cycle of a star much more massive than the Sun.
Click “Check Mark Scheme” to compare your answer, Nebula → Protostar → Main sequence star → Red supergiant → Supernova → Neutron star or Black hole.
- Q2
Explain how red-shift provides evidence for the Big Bang.
Click “Check Mark Scheme” to compare your answer, Light from distant galaxies is shifted to longer wavelengths (red-shift). The further away a galaxy is, the greater the red-shift, meaning it is moving away faster. This implies the whole universe is expanding from a single point.
- Q3
Why is the velocity of a satellite in a circular orbit constantly changing, even if its speed is constant?
Click “Check Mark Scheme” to compare your answer, Velocity is a vector quantity (it has direction). Because the satellite is moving in a circle, its direction is constantly changing, so its velocity is constantly changing.
Common Exam Questions (3)
What is the Big Bang Theory?
The Big Bang theory states that the universe began approximately 13.8 billion years ago from an extremely hot, dense, and tiny initial region, and has been expanding and cooling ever since.
What is red-shift?
Red-shift is the observed increase in the wavelength of light from distant galaxies (shifted toward the red end of the spectrum) caused by galaxies moving away from us as space expands; more distant galaxies exhibit greater red-shift, showing they are receding faster.
What keeps planets in orbit around the Sun?
Gravitational attraction between the Sun and a planet provides the inward centripetal force required to continuously change the planet's direction of motion, keeping it in a stable orbit.
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