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Tags
bio/astro
cegep/3
Word count
294 words
Reading time
2 minutes
  • nebula: galactic cloud
  • solar system: stars and planets that orbit it
  • astrobiology: study of life in the universe

2025-08-22

  • Criteria:
    • Habitable zone
    • Adequate temperature
      • Liquid water
      • Eccentricity of planet not too high

2025-08-27

source of elements

  • Big Bang nucleosynthesis
    • Matter made from extremely intense light within the first 5 minutes => proton (hydrogen), electron & neutron
    • Nuclear fusion: collision of hydrogen within the first few hours => helium
  • Low mass star (red giant)
    • CNO cycle => helium
  • High mass star (supergiant)
    • Helium capture => elements until iron
    • Star explodes to become neutron star => gold & uranium
  • White dwarf supernovae => iron-group elements
  • Radioactive decay => radioactive elements
  • Neutron star
    • => neutron
    • R-process: merge of neutron stars => radioactive elements
  • Cosmic ray spallation => beryllium & bore
  • Human-made => synthetic elements like technetium

2025-08-29

escape speed

Minimum speed needed for an object to escape the gravitational field of another object

vi=2GMR

- Proof

Ki+Ui=Kf+Uf12mvi2=GMmRvi=2GMR

[!example]+ Determine the escape speed of the moon.

vi=2GMmoonRmoon=16.6710117.34810221737000=2.375ms

Kepler's Laws

First Law

The orbit of planets around the sun is an ellipse.

[!abstract] eccentricity
Measure of how ellipse-like the orbit is

Second Law

A planet sweeps out equal areas of its orbit in equal times.
Aka. conservation of angular momentum

Third Law

More distant planets orbit at slower speeds, obeying the relationship

T2=4π2G(m1+m2)a3

Therefore, to determine the mass of a planet:

mpsini(vsini)1e228.4ms(T1year)13(MM)23MJ

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