# Introduction to Astronomy Note
NTNU 星星月亮太陽─天文漫談
##### [Back to Note Overview](https://reurl.cc/XXeYaE)
###### tags: `NTNU` `通識` `Science and Life` `Introduction to Astronomy`

##### [Moodle_Lecture Notes](https://reurl.cc/gvz284)
## 88 constellation
## Glossaries
Horizon 地平線
Zenith 頂點
Meridian 子午線
Celestial Pole 天極
Celestial Equator 天體赤道
latitude 緯度
Ecliptic 黃道
Axial Tilt 軌道傾斜
Summer solstice 夏至
Winter solstice 冬至
Spring equinox 春分
Autumnal equinox 秋分
Polar region 極圈
Analemma 日行跡
Sundial 日晷


## Diurnal Motion 週日運動
### Earth Spin

## Earth Orbital Motion 地球軌道運動
### Ecliptic
The ecliptic is the mean plane of the apparent path in the
Earth's sky that the Sun follows over the course of one year
### Earth Orbit
### Season
Axial Tilt + Earth Orbit = season
sun from left to right = north pole

## Sidereal Day 恆星日 vs. Solar Day 太陽日

| | Sidereal Day | Solar Day |
|:--------:|:--------:|:--------:|
|Degree|360°|361°|
| Time | 23hr 56min| 24hr |

[說明](http://www.phys.ncku.edu.tw/~astrolab/e_book/nite_sky/captions/sidereal_solar.html)

## Earth Region
### Tropic of Cancer 北迴歸線
When this line of latitude was named in the last centuries BC,
the Sun was in the constellation Cancer at Summer solstice.
### Tropic of Capricorn 南迴歸線
When this line of latitude was named in the last centuries BC,
the Sun was in the constellation Capricornus at Winter solstice.
## Analemma 日行跡
Earth Orbit + Axial Tiltx + Ellliptical Orbit

In astronomy, an analemma is a diagram showing
the position of the Sun in the sky,
as seen from a fixed location on Earth
at the same mean solar time,
as that position varies over the course of a year.
The diagram will resemble the figure 8.
Globes of Earth often display an analemma.

### Analemma on Mars

## precession of the earth 歲差

### Zodiac and Astronmy
#### Zodiac
[wiki_Astrological sign](https://en.wikipedia.org/wiki/Astrological_sign)

{%hackmd @sophie8909/B1cYiAppr %}

#### Polaris 北極星
Polaris will not be "Polaris" any more.

9/25
## Moon and Earth

### real scale
picture of the distance between earth and the moon and the scale of it
•••••••••
### phase
the animation of how the phase form

### tide
picture of the tide caused by moon's phase
picture of the tide during a day
picture of the tide during a month(one month varations)
picture of the tide during a yaer(one month varations)
picture of how tide form(include earth and the moon)
picture of elliptic earth orbit(exaggerated)
picture of elliptic solar orbit(exaggerated)
### Eclipse

#### Solar Eclipse

picture of eclipse path


#### Lunar Eclipse

earth shine

### Synchronous rotation 同步旋轉

Moon and Earth rotation（自轉）
Q：Why Synchronous?
A：Don't know(I think it is Tidal locking)
#### Libration 天平動

### Moon Origin
How was the moon created？
[How the Moon Formed: 5 Wild Lunar Theories](https://www.space.com/25322-moon-formation-wild-theories.html)
- Fission
- Capture
- Co-formation
- Colliding planetesimals
- Giant impact
## Tools of Modern Astronomy

- Angle
- unit of angle=degree
- Angular Separation
- Angular Distance
- Angular Size
* d=2Dtan(δ/2)
* Arc Approx d=D*
* d=Dδ
* δ～0.5degree(30arc min)～0.0087266randian
- Distance
- AU
- lightyear
- 1parsce(pc)～3.26lightyear(ly)
* D(pc)= 1/angle(arc second)
* The angle that is used in the equation is formed by earth-star line and Sun-star line
- Redshift(z)～4000Mpc
* d=v/H$_o$=cz/H$_o$
* v=recessional velocity
* z=redshift
* H$_o$=Hubble constant
## Solar System
### History and Background
#### Kepler's law
1. The orbit of every planet is an ellipse with the sun at a focus.
2. A line joining a planet and the sun sweeps out equal areas during equal intervals of time.
3. The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.
$\varpropto$

#### Retrograde motion
Planets move backwards in the sky.

### Planet
#### Mercury
highlights of what we know about Mercury
- Not much is known, because it is difficult to reach
- Very eccentric orbit(eccentricity~0.2)
- No satellite
- No thick atmosphere
- Similar to Earth Moon
- Dense(5.427g/cm^3^: second highest in solar system)
- Relatively strong magnetic field
- Suspected .........
<!---->
#### Venus
highlights of what we know about Venus
- Earth twin, almost the same size
- Atmosphere is very thick(~90atm)
- Atmosphere is made of C0$_2$
- Surface is very hot(~400 ℃)
- Magnetic field is weak
- No evidemce of plate tectonics
- Rain of Surfanic Acid(H$_2$SO$_4$)

#### Mars
highlights of what we know about mars
+ 1/100 of earth air pressure
+ Mostly CO$_2$
+ No Ozone layer
+ Possible water in the past
+ Temporary surface water ?
+ No current sign of life
+ Water ice and CO$_2$ ice
+ Roman god of war
+ Smaller than the Earth (almost half the size of Earth)
+ Percival Lowell(USA) thought that there are canals on Mars{Mariner 4 proved wrong}

#### Jupiter
- Atmosphere is mainly made of Hydrogen
- iquid oceans may exist under Euroqa's icy surface
- Galileo made the first observation of ammonia clouds in another planet's atmosphere. The atmosphere creates ammonia ice particles from material coming up from lower depths.
- Ganymade possesses its own, substatial magnetic field.
- Europa,Ganymede and Callisto may have a liquid-saltwater layer under the visible surface
#### Saturn

### Space probes to Mars
- Mariner 4(水手四號) 1964
- First Mars flyby
- Viking 1 & 2(海盜一號&二號) 1975-1976
- First successful landing on Mars
- took photos on the surface
- conducted soil experiments
- Mars Pathfinder & Sojourner(火星拓荒者&旅居者號) 1996-1997
- First rover(Sojourner) landing on Mars
- Mars Pathfinder is just the carrier
- took lots of pictures and analyzed the chemical properties near the lander
- Spirit / Opportunity (精神號/機會號) 2004
- Both rovers
- climbed montains
- saw little tornados
- saw Earth from Mars
- saw the two moons of Mars
- Spirit died in 2010
- Opportunity died in 2019
- Phoenix(Lander)(鳳凰號) 2008
- can dig
- try to find permafrost -> water
- Curiosity(好奇號) 2012
- rover

### Space probes to Venus
- Mariner 2 & 5(水手)
- flyby mission
- Mariner 10
- flyby mission
- also went to mercury
- Venera 7 & 8(金星計劃)
- lander
- no cameras
- Venera 9 & 10
- lander
- colorless camera
- Venera 13 & 14
- lander
- full color camera
- survived for ~2 hrs
- Venera 15 & 16
- satelite
- radar mapper
- Pioneer-Venus 1 & 2(先鋒金星)
- satelite
- radar mapper
- Magellan(麥哲倫號)
- satelite
- radar mapper
### Space probes to Mercury(they all went to Venus)
- Mariner 10(水手)
- first gravatiy assist probe
- flyby
- Messenger(信使號)
- satelite
- gravatiy assist
### Space probes to Jupiter
- Pioneer 10 & 11(先鋒)
- flyby
- has golden plated board with human info
- Pioneer 11 went to Saturn
- Voyager 1 & 2(航海家)
- flyby
- both went to Saturn
- Voyager 2 went to Uranus & Neptune
- Galileo mission(伽利略號)
- satelite
- Venus gravatiy assist
- has entery probe
### Space probes to Saturn
- Voyager 1 & 2(航海家)
- flyby
- both went to Juputer
- Voyager 2 went to Uranus & Neptune
- Cassini(satelite)-Huygens(lander) mission(卡西尼-惠更斯號)
- Venus gravatiy assist
- went to Venus & Jupiter
- saw weird hexagon on the pole
- landed on Titan
- speculation of lakes on Titan

## Extended Solar System
{%hackmd @NTNUCSIE112/solarsystemnote %}
- Small solar system bodies(SSSB) ~minor planets
- Trans Neptunian Objects(TNO)
- Kuiper Belt Objects(KBO) (stable orbit)
- Oort Cloud (spherical)
- Hills’ Cloud
- Scattered Disk (dynamic/unstable orbit)
- Centaurs
- Asteroids

### The outermost planet - Pluto
- New Horizon ： First to take a pic

### Asteroids
- 221945+ asteroids are numbered
- ~15000 have names
- Gaileo Spacecraft
- made the first flyby of asteroids en route to Jupiter
- 1991 951 Gaspra


- 1992 243 Ida

### Comets
## Stars
### Star Life - Stellar Evolution
#### Red Giant Star
#### Planetary Nebula
#### Supernova
#### Neutron Star
#### Pulsar(aka Neutron Star)
Has this name because it has streams coming out of it and it spins very fast. So it looks like it 'pulses'.
#### Black Hole

##### [Solar System Note](https://hackmd.io/@NTNUCSIE112/solarsystemnote)
{%hackmd @NTNUCSIE112/astabb %}
{%hackmd @NTNUCSIE112/astch %}