Space Physics

• The solar wind is the flow of charged particles from the sun.
• Earth's rotation


  Planet Earth rotates on its axis every 24 hours, causing day and night cycles
• Earth's axis of rotation

  • Tilted at an angle of 23.5 degrees, which affects the seasons
• Earth's orbit


  Orbits the Sun, taking 365 days to complete one revolution
• Tilt of Earth's axis and its orbit around the Sun


  Determine the seasons
• Moon's orbit


  Orbits Earth, taking about 30 days to complete one orbit
• Moon's orbit


  Affects the tides on Earth and the phases of the Moon
• Calculating orbital speed


  Formula: 2 pi r / t, where r is the radius of the orbit and t is the orbital period
• Gravitational field strength


  Depends on a planet's mass and decreases as you move farther away from it
• Orbital speed of a planet

  Depends on its distance from the Sun
• Formation of the Solar System

  Accretion model: Vast cloud of dust and gas spinning in outer space, gravitational force attracts gases towards the center forming an accretion disk, hydrogen atoms collide and fuse together to form helium, releasing heat and light creating a protostar, protostar becomes a stable star when outward force of heat from nuclear fusion balances the inward force of gravity, dust and rocks start to clump together forming protoplanets, heat from the Sun pushes out lighter elements resulting in the formation of small and rocky planets close to the Sun and large and gassy planets far from the Sun
• Sun


  A medium-sized star that emits infrared waves, visible light, and ultraviolet radiation
• Star life cycle


  Start as nebulae, collapse due to gravity, heat up and form protostars, eventually become stable stars, when a medium-sized star like the sun runs out of fuel, it turns into a red giant, expanding and destroying nearby planets, after the red giant phase, the star collapses again and becomes a white dwarf, which eventually turns into a black dwarf, very large stars become red supergiants, which explode in a supernova, scattering heavy elements throughout the universe, the remnants of a supernova can form a black hole or a neutron star, depending on the mass of the original star
• Universe


  Vast and consists of billions of galaxies, our own galaxy, the Milky Way, being approximately 100,000 light-years in diameter
• Big Bang Theory


  Suggests that the universe started as an infinitely small dot of mass and energy and has been expanding ever since
• Redshift


  The stretching of light waves as a star or galaxy moves away from us, providing evidence for the expansion of the universe
• Doppler Effect


  The wavelength of sound or light changes when the source of the wave is moving relative to the observer
• Cosmic Microwave Background Radiation


  The leftover radiation from the Big Bang, which has been stretched to microwave wavelengths due to the expansion of the universe
• Hubble Constant


  A measure of the expansion rate of the universe, calculated by dividing the speed at which a galaxy is moving away from us by its distance from us, the current value is approximately 2.2 × 10^-18 seconds^-1
• Age of the Universe

  Estimated to be around 14.4 billion years, based on the inverse of the Hubble constant
• The universe is expanding, and the evidence for this is the red-shifting of light from distant galaxies
• The galaxies themselves aren't moving through space, but rather the space between us and the galaxies is expanding
• Absorption spectra


  Show the wavelengths of light that are absorbed by chemicals in the atmosphere
• Absorption spectra of distant galaxies

  Shifted towards the red end of the spectrum compared to the absorption spectra of light emitted from the Sun
• The further away a galaxy is, the more quickly it will appear to be moving away
• Models are useful for understanding difficult concepts, but they have limitations
• The universe is currently expanding, so it must have been smaller in the past
• Big Bang theory


  Proposes that the universe began as a tiny, dense, and hot space that suddenly exploded and started expanding