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- All telescopes that scientists use, look at electromagnetic radiation. The are the radiation that travels at light speed and have electromagnetic waves.
- Example: radio waves, visible light, gamma rays
- A telescope that uses a lens to collect light.
- A telescope that uses mirrors to reflect the light into an eyepiece.
- A man made object that orbits around Earth, the Moon, or any other celestial body.
- Example: man made TV satellites orbit the Earth
- A natural celestial body that orbits another celestial body of a larger size.
- Example: Titan (satellite) orbits around a larger celestial body (Saturn)
- A sort of observatory that orbit other planets for the purpose of gathering information about said planet. They take high resolution pictures, and have a relatively short life span.
- Example: Pioneer Venus, orbited Venus to collect data on its atmosphere and surface
Challenges of Space Travel
- - everything is so far away
- - Humans need food and water for long trips
- - space is extremely cold
- - spacecrafts can break down and leave humans stranded in space
A stationary observatory on the surface of a planet. Can last a long time, but only sample a small portion of the planet since they cannot move.
Solar Nebula Theory
- This theory states that planets and stars form together.
- A protostar forms in the centre with a nebula surrounding it. Gravity sets the nebula in a spinning motion around the protostar.
- The spinning causes the nebula to contract, causing tiny grains to collect.
- Eventually they collect enough to become rocky lumps called planetesimals.
- If the planetisimals survive bumping into other planetesimals, they will eventually become planets in a solar system.
Evidence of the Solar Nebula Theory
- - Collisions are bound to happen when things are in motion. As proof of these collisions, we have the crater filled surfaces of the Moon and Mercury to look.
- - Over time as the nebula spins, the nebula would spin on a flat plane. Scientists have seen flat planed nebulae around young stars outside our solar system.
- - Planets are by products of the formation of stars. There have been over 300 extrasolar planets found. Planets outside our solar system.
- A celestial body mainly made of hydrogen and helium and hot.
- Example: Betelgeuse, Sun, Vega
- Vast cloud of dust and gas that is theorized to be the birthplace of stars and planets.
- Example: Orion Nebula located in the constellation Orion
- A young star
- Hot, and condensed object forming at the centre of a nebula.
- When stars are being formed they collapse causing the gases to compress. This compression causes the star to heat up.
- At 10,000 degrees Celsius, hydrogen atoms fuse to create helium atoms.
- This usually only occurs in the core of stars since very high temperatures and pressure are necessary. It is a nuclear reaction.
- Stars use hydrogen as fuel to burn
Since the Sun is made of gas it has no definite surface. The photosphere describes the 1000s of kilometers deep area recognized as 'the surface'
When charged particles affect the Sun's photosphere, they go to the area with the strongest magnetic field. These are the areas where the Sun is relatively cooler than the surrounding area.
When the Sun ejects intense streams of charged particles into space.
- Once the solar flare is in space and is moving away from the Sun, it is called a solar wind.
- Solar flare is the event of ejecting the stream, solar wind is the stream outside the sun.
Importance of the Sun
- -The Sun is needed for all life on Earth
- - Sun contributes to our shelter and food
- - Solar energy powers the wind and ocean currents
- - Sun is the cause of weather on Earth
- - Sun is the source of photosynthesis
- -The Sun heats the Earth up
- A quantifiable measure of a star's brightness.
- - energy output of a star per second.
- - The star's power in joules/second
The observable brightness of a star if it were 32.6 light years from Earth.
How bright the star is as seen from Earth
An instrument that creates a pattern of colours and lines from a narrow beam of light onto a photographic plate/ digital detector.
- Wavelengths of a spectrum, shown with lines.
- Spectral lines identify specific chemical elements in star's photosphere.
Hertzsprung-Russell (H-R) Diagram
- A graph that compares stars according to their properties. The luminosity is on the y axis, and the temperature and colour is on the x axis.
- This graph shows that
- - most cool stars are dimmer than bright stars
- - hot stars tend to be larger than cool stars
- A diagonal band on the H-R Diagram that run from the top left (hot, bright) to bottom right (cool, dim) side of the graph.
- 90 percent of stars are in this range including the sun.
- It's sort of like a trend line.
- Stars outside the main sequence are usually cool, but bright supergiants located above the main sequence.
A small, dim hot star that no longer produces energy.
A violent explosion after a star has run out fuel, where the outer layers are blown off.
These form when stars are at 12-15 solar masses. The core collapses to 20 km wide. There is so much pressure that the electrons are squeezed protons causing the star to become a star so dense, that only neutrons exist in its core.
How Low-Mass Stars (Red Dwarfs) Evolve
- Red dwarfs are stars that are smaller and cooler than the Sun.
- They consume their hydrogen over 100 billion years
- Red dwarfs run out of fuel and dissipate. Whatever remains is a hot white dwarf that doesn't produce any energy but is cooling down.When they do cool down, they become black dwarfs. Essentially cool embers of their former selves.
How Intermediate-Mass Stars Evolve
- Intermediate-Mass Stars such as our Sun, consume their hydrogen over the course of 10 billion years.
- After the fuel runs out, the core collapses causing the temperature to increase and the outer layers to expand.
- These outer layers would be cooler, so the Sun would become a large, red star, called a red giant.
- The layers simply dissipate into space since the outer layers can no longer be held onto by the core.
- What's left is a white dwarf.
How High-Mass Stars Evolve (12 + solar masses)
- These stars consume their fuel faster than intermediate-mass stars.
- The core heats up to even higher temperatures.
- In the core, fusion causes heavier metals to appear white the outer layers expand to become a super giant.
- Iron cannot release energy though fusion so the star collapses violently, with shock-waves going through the star. This explosion is called a supernova.
- The elements are flung into space to form new stars and planets.
- For black holes to form, the star has to more than 25 solar masses.
- After the supernova explosion, the gravity becomes so crushing that nothing can compete with it. Whatever is left of the explosion is crushed into a black hole.
- A black hole is a patch of space with no volume, but it has mass.
- The gravitational force is so overwhelmingly powerful that not even light can escape it.