Unit 16: Astronomy and space science Learning aim A Understand the fundamental aspects of the solar system
Contents page Note: anywhere you see a capital D means you MUST draw a diagram.
Radiative zone Corona Core Convective zone Chromosphere Photosphere
You need a copy of this in your notes Page 6.
Hydrostatic equilibrium Hydrostatic equilibrium occurs when the force due to gas pressure exactly balances out the force due to gravity.
Sun s magnetic field
Sunspots
Life cycle of a star (D)
Hertz sprung-russel diagram Stars DO NOT progress along their stage! What do you notice about this axis?
Spectral classes The Sun has a surface temperature of about 5,300 K. Spectral Class Intrinsic Color Temperature (K) O Blue Over 25,000 B Blue 11,000 25,000 A Blue-white 7,500 11,000 F White 6000-7,500 G Yellow-white 5,000-6,000 K Orange 3,500-5,000 M Red Under 3,500 TYPE Ia Ib II III IV V VI Star Very luminous supergiants Less luminous supergiants Luminous giants Giants Subgiants Main sequence stars (dwarf stars) Subdwarf
Anatomy of the Earth Crust Outer core Mantle Inner core
Composition of Earth s Atmosphere What can you remember?
Earth s tilted axis The Earth s axis is tilted by 23.5.
Day and night
Solar and Sidereal days
Orbits
These orbits are NOT circular:
Kepler s Laws 1. All planets move in elliptical orbits with the Sun at the centre. 2. A line that connects a planet to the Sun sweeps out equal areas in equal times. 3. The square of the period of any planet is proportional to the cube of the semi-major axis of its orbit.
Eclipses
Moon phases
What is this? Have you even see this before?
You only ever see one side of the Moon, why?
The Moon is tidally locked. It s orbital rotation is the same as the time it takes to orbit Earth.
Centripetal force The planets are accelerating just fast enough to remain in their orbits.
Centrifugal force
Van Allen Radiation Belts
Formation of the Aurora Borealis
The Aurora Borealis or Northern lights as viewed from space.
The aurora seen on Earth
Forces involved in the Solar System The 3 mains ones: Gravitational forces Centrifugal forces Centripetal forces
The centripetal force arises from the gravitational pull on a planet from the Sun. (E.g. water in a bucket, if you swing a bucket full with water fast enough, the water will remain in the bucket and the string attached to the bucket will remain taut - this is because of the centripetal force.)
The centrifugal force arises from the planet orbiting the Sun at a great speed. (E.g. a mixture put into a centrifuge, the mixture separated out depending on the density of the substances initially mixed together.)
Inner and outer planets Can you remember the planets in order? You will need to find a diagram of each planet for your assignment.
Moons of the Solar System
Planetary ring systems
Features and characteristics of other Solar System objects Asteroids Meteors Comets Kuiper belt Oort cloud
Asteroid belt
Meteor
Comets
Kuiper Belt
Oort Cloud
Measuring astronomical distances There are a few methods you need to write about: Trigonometric Parallax Cepheid variables as standard candles Eclipsing binaries
Trigonometric parallax Limitations? Inaccurate for distances greater than 65 light years.
Units
Cepheid variables Brighter stars have longer periods
We can use an equation and the inverse square law to calculate the distance:
Cepheid variables can be used to measure distances of 20 million light years. http://hyperphysics.phyastr.gsu.edu/hbase/astro/cepheid.html
Eclipsing binaries
Evidence for an expanding Universe?
Redshift and blue shift
Hubble s Law Hubble s Law The further away a galaxy is from another point in space, the faster it appears to recede, and therefore, the Universe is expanding.
Determining the age of the Universe: Age of Universe = 1 H 0
Possible fate of the Universe based on density: https://futurism.com/four-ways-the-universe-could-end/
Cosmological theories of the present day Big Bang theory. Olbers paradox. Steady state.
Big Bang Theory
Olbers Paradox Is the night sky infinitely bright?
Reasons why the night sky is not infinitely bright: 1. There is too much dust to see the distant stars. 2. The Universe only has a finite (opposite of infinite) number of stars. 3. The position of stars in not even stars could hind behind one another. 4. The Universe is expanding. 5. The Universe is young meaning distant light has not reached us yet.
Steady state theory https://universea ndphysics.wordp ress.com/2017/0 5/08/steadystate-theoryrejected/
Note Anything with a name must have a capital letter: Sun Moon (if you are talking about ours) Earth Solar System