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Space and Astronomy Flashcards
Free GCSE and A Level Physics Study Cards
From the solar system and stellar life cycles to redshift, the Big Bang, and dark matter, these free Physics flashcards cover all the key space and astronomy topics for GCSE and A Level.
Question
What is a light year?
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Answer
The distance light travels in one year in a vacuum — approximately 9.46 × 10¹⁵ metres. Used to measure distances between stars and galaxies.
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Question
What is the order of the planets from the Sun?
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Answer
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. (My Very Educated Mother Just Served Us Nachos.)
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Question
What is a star's main sequence stage?
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Answer
The longest phase of a star's life where hydrogen is fused into helium in the core. The outward radiation pressure balances gravitational collapse. Our Sun is currently in the main sequence.
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Question
What happens to a star like the Sun after the main sequence?
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Answer
It expands into a red giant (as hydrogen runs out, helium fusion begins), then sheds its outer layers forming a planetary nebula, leaving behind a white dwarf.
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Question
What is the fate of a massive star?
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Answer
Expands into a red supergiant → supernova explosion → if the remnant core is massive enough it forms a neutron star; if extremely massive, a black hole.
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Question
What is a black hole?
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Answer
An object so dense that its escape velocity exceeds the speed of light — nothing, including light, can escape its event horizon. Formed from the collapsed cores of very massive stars.
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Question
What is redshift and what does it tell us?
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Answer
The stretching of light wavelengths from objects moving away from us. Distant galaxies show redshift, indicating the universe is expanding. The greater the redshift, the faster they recede.
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Question
What is the Big Bang theory?
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Answer
The universe began ~13.8 billion years ago from an extremely hot, dense singularity that expanded rapidly. Evidence: cosmic microwave background radiation, redshift of galaxies, abundance of light elements.
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Question
What is Hubble's Law?
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Answer
The recession speed of a galaxy is proportional to its distance: v = H₀d, where H₀ is the Hubble constant. Provides evidence that the universe is expanding.
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Question
What is cosmic microwave background (CMB) radiation?
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Answer
Low-energy microwave radiation filling the universe uniformly — the cooled remnant of intense radiation from the early universe (~380,000 years after the Big Bang). Strong evidence for the Big Bang.
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