Science Revision Semester 2 Exam 2024 PDF

Science revision semester 2 exam 2024 The universe, stars and galaxies **Identify the differences between the main components of the universe (Galaxies, stars and solar systems)** Solar systems orbit around their galaxies just as planets orbit around their suns. The Universe is the largest. **Id...

Science revision semester 2 exam 2024 The universe, stars and galaxies **Identify the differences between the main components of the universe (Galaxies, stars and solar systems)** Solar systems orbit around their galaxies just as planets orbit around their suns. The Universe is the largest. **Identify 3 types of galaxies** Elliptical, spiral, and irregular. **Distinguish between spiral, elliptical and irregular galaxies.** Elliptical galaxies are shaped like spheres or cucumbers and contain old stars. Spiral galaxies have a central disk surrounded by spiralling arms and possess new stars. Irregular galaxies have no distinct shape and have both old and new stars. **Identify the Milky Way galaxy as a spiral galaxy** When you look toward the galactic centre with your eye, you see a long, thin strip. This suggests a disk seen edge-on, rather than a ellipsoid or another shape. We can also detect the bulge at the centre. **Define light year** a unit of astronomical distance equivalent to the distance that light travels in one year **Describe how the process of nuclear fusion provides energy to stars.** Nuclear fusion is the process of forcing together two light atomic nuclei and creating a heavier one, in the process taking a tiny amount of matter and turning it into massive amounts of energy. **Describe the lifecycle of small, medium and large stars** A smaller star, like the Sun, will gradually cool down and stop glowing. During these changes it will go through the planetary nebula phase, and white dwarf phase. After many thousands of millions of years it will stop glowing and become a black dwarf. A massive star experiences a much more energetic and violent end, going through a supernova and then transitioning into its final stage of being either a neutron star for medium stars or a blackhole for large stars. **Relate star temperature to colour** The surface temperature of a star determines the color of light it emits. Blue stars are hotter than yellow stars, which are hotter than red stars. **Compare and contrast apparent and absolute magnitude (brightness) of stars** absolute magnitude -- a measure of how bright a star would be if it were seen from a standard distance. apparent magnitude -- the brightness of a star as seen from Earth. **Describe the life cycle of our star -- the sun** A smaller star, like the Sun, will gradually cool down and stop glowing. During these changes it will go through the planetary nebula phase, and white dwarf phase. After many thousands of millions of years it will stop glowing and become a black dwarf. **Describe the Big Bang Theory and how it contributed to the formation of the Universe.** Starting from extremely high density and temperature, it exploded and space expanded, the universe cooled, and the simplest elements formed. **Describe how red shift and cosmic background radiation provide evidence for the Big Bang theory** an indication that these galaxies are moving away from us and that the universe is expanding. The Cosmic Microwave Background (CMB) is the cooled remnant of the first light that could ever travel freely throughout the Universe