diff --git a/Grade 9/Science/SNC1DZ/Unit_5_Astronomy_Study_Sheet.md b/Grade 9/Science/SNC1DZ/Unit_5_Astronomy_Study_Sheet.md index a1abbea..d84655f 100644 --- a/Grade 9/Science/SNC1DZ/Unit_5_Astronomy_Study_Sheet.md +++ b/Grade 9/Science/SNC1DZ/Unit_5_Astronomy_Study_Sheet.md @@ -1,5 +1,36 @@ # Unit 5: Astronomy +## Terms +- `AU` = Astronmical Unit, which is the distance between the sun and the Earth = $`1.5 times 10^8`$ +- `1 Light year` = $`9.46 \times 10^{12}`$ +- Our milky way is a spiral yeet (forgot full lesson, think this is all you need). + +## Layers of the Sun +|Layer|Temperature|Description| +|:----|:----------|:----------| +|Corona|5800oC|- Gleaming white, halo-like - extends millions of km into space| +|Chromosphere|65 500oC|| +|Photosphere|5 500oC|- The layer just below the Chromosphere where the light we see originates| + +## Inside Of The Sun +|Zone|Descrption| +|:---|:---------| +|Convection Zone|- The `outermost` ring of the sun, comprosing of the `30` percent of its radius| +|Radiative Zone| - The section immediately `surrounding` the core, comprising `45` percent of its radius| + +### Core +- `Hottest` part of the sun, reaching $`15,000,000^o`$C +- Energy released by **nuclear fusion** continues to move outward until it reaches the photosphere +- #### Compostion + - **75%** `hydrogen` + - **25%** `helium` (with small amounts of other gases) + +### Nuclear Fusion +- The sun is made out of **hydrogen** atoms. +- The Sun’s energy comes from the **nuclear fusion** reactions that occur in the **core** of the Sun. +- **High temperatures** and **pressure** cause particles to collide at extremely high speeds. The **hydrogen** atoms of the sun fuse together forming **helium** atoms. +- Gives off **enormous amounts of energy**. + ## Suns Affect on Earth ### The Aurora Borealis (Northern Lights) @@ -70,4 +101,85 @@ - Most comets have 2 tails; - `gaseous tail` - `dust tail` -- \ No newline at end of file +- + + +## Big Bang Theory +- It happened around 13.7 billion years ago when the Universe was a infintely dense point. +- Formed from an extremely dense singularity (centre of a black hole) +- Prior to that there was nothing + +### Evidence to support theory +- #### Redshift and Hubble’s Law + - Hubble observed the line spectra from many different galaxies in sky, and most of spectra for galaxies were shifted towards the red end of the spectrum, a red shift + - Hubble concluded that if most of galaxies were redshifted, they must be moving in all directions and the Universe is expanding from a single point +- Space between galaxies expand, not the galaxies themselves +- **Dark Matter:** the rest of the Universe appears to be made of a mysterious, invisible substance called dark matter (25%) and a force that repels gravity known as dark energy (70%) + - 90% of matter in and between galaxies is of an unknown form that does not emit or absorb light + - Can be detected through its gravity by the way it affects objects we can see + - Without dark matter, normal matter would have been unable to clump and form stars and galaxies + +## Apparent and Absolute Magnitude +- `Luminosity`: Total amount of energy produced by a star per second +- `Apparent Magnitude` + - Brightness of a star in the night sky as they appear on Earth + - The lower the number, the brighter the star is +- `Absolute Magnitude` + - Brightness of a star as if they were located 33 ly from Earth + - The lower the number, the brighter the star is + +## Size of stars changes their lifestyle + +### Hertzsprung Russel Diagram +- The Hertzsprung-Russell Diagram is a graphical tool that astronomers use to classify stars according to their luminosity, spectral type, color, temperature and evolutionary stage. +- Basically plotting the class of the stars based on their lumionsity (how bright they are) and their temperature (how hot they are). +- + +### Low Mass Stars +- With less gravity, burns hydrogen fuel slowly and lasts for 100 billion years, matures into red dwarf, and when fuel for nuclear fusion runs out, becomes a white dwarf + +### Medium Mass Stars +- Lasts for 10 billion years +- When a medium mass star runs out of fuel, it collapses under its own gravity, collapse heating up and pressure increases causing nuclear fusion of helium +- Star expands and becomes a red giant, eventually burning out to form a white dwarf +- When white dwarfs become cool enough to no longer emit heat or light, they become black dwarfs, however since the time required for a white dwarf to reach this state is older than the Universe, no black dwarfs currently exist + +### High Mass Stars +- Lasts up to 7 billion years, 10 times size of our Sun +- When high mass star runs out of fuel it collapses and expands to form a supergiant +- Supergiants end in a violent massive explosion called a supernova +- End results - Cosmic debris (nebula), a neutron star (or pulsar) or a black hole + +### Supernova +- Supergiants that run out of fuel end in a massive explosion +- Nuclear fusion reactions occur and new elements form and explode into space +- Debris from explosion is source for a new nebula, and what happens to the stars remaining core depends on original size of the star + +### Neutron Stars +- Remaining core of a supergiant that is less than 40 times the size of our Sun +- Also called a pulsar, very dense matter made of neutrons + +## Black Holes +- Remaining core of a supergiant that needs to be more than 40 times the size of our Sun +- Core of the supergiant after a supernova is so dense that its gravitational pull sucks in space, time, light, and matter +- Thought to be at the centre of all galaxies + +## Formation of Stars +|Stage|Description|Picture| +|:----|:----------|:------| +|1. Birth and Early Life|- Life for a star begins in a **nebula**, which are HUGE, unevenly distributed clouds of dust and gases (**mainly H** & **He**).
- Denser areas gather surrounding material due to greated **gravitational pull**
- As material is added, gravity increases , drawing in even more material… then density and pressure increase as well.
- This core and surrounding material start spinning more as they continue to condense. (like a figure skater)
- Any surrounding dust and gases that aren’t drawn into the core will **flatten out** to look like a disc around the core. (the natural tendency for all spinning objects)
- **Temperature begins to rise** due to atomic collisions and start emitting **low level energies like microwave & infrared**.
- This is now called a protostar.|| +|2. Main sequence phase (adult star)|- As core temperature reaches a critical point (15 million °C), **NUCLEAR FUSION begins** and it becomes a *star**.
- H atoms join to form He atoms, releasing enormous amounts of **high energy radiation**, which also **emits light energy.**|| +|3. Old Age|- Once a star’s core has **used up its H**, it fuses **He**, which **releases even more energy**.
- This causes the star to swell into a **red giant** or **red supergiant** depending on their original mass.|| +|4. Death|- An average star “dies” when it doesn’t have enough energy to continue **nuclear fusion** (usually once it forms **carbon**).
- For a star like our sun, the core shrinks/collapses, releasing the outer layers of gases.
- The `small, hot, and dense core` becomes a **white dwarf**, while the outer gases form a new **nebula** around it. This combo is called a **planetary nebula**.
- A more massive star will do fusion up until **iron** then collapse, but the outer layers will explode off this iron core to form a **supernova**.|| +|5. Remains|- **Small red giants** collapse & shrink into a **white dwarf**, which will slowly cool down and eventually **fade out** (no energy emitted) to be a **black dwarf**.
- **Large red giants** explode as a **supernova**, & will form either a **neutron star** or even a **black hole** if the core has enough mass.| + + + +## Space Composition +- + +### Dark Matter +- The rest of the universe appears to be made of a mysterious, invisible substance called dark matter (25 percent) and a force that repels gravity known as `dark energy` (70 percent). Scientists have not yet observed `dark matter` directly. +- `90%` of matter in and `between` galaxies is of an `unknown` form that `does not emit or absorb light (so we can’t see it)`. +- It can be detected through its `gravity` by the way it `affects` objects we can see. +- Without dark matter, `normal matter` would have been unable to `clump` and `form` stars and `galaxies` - and US!