宇宙学和天文学
large scale ( universe )
Our earth is 12,700 diameter across
Our sun is 100 times of diameter of the earth
1 AU ( astronomical unit ) is 150 million km
1 light year = the distance light travels in a year
The universe is 13.7 billion years old
The milky way gaxaly is 100,000 light years across and it has 200-400 billion stars
The observable universe is approximately 93 billion light-years in diameter.
a light year is ~63000 AU
small scale
Even though the milky way seem like its full of stars and planets ,a chuck of it are empty spaces, no stars , no planets , nothing . That's how big the milky way is.
Our universe is much bigger than the observable universe as it is constanly expanding
1 meter is 100 cm
1 mm is 10 cm
1 μm(mircometre) is 0.001 mm
A nanometer is one billionth of a meter
a angstrom is 0.1 nanometre.
An average human hair is about 60,000 nanometers thick
a femtometer is a a quadrillionth of one metre.
a hydrogen atom is roughy 1 angstrom
an atom is mostly empty space
The largest distance that humans can relate to is about 100 miles ( 160.934 km )
Earth's circumference is about 40,000 kilometers
To circumnavigate the Earth, it would take 40 hours to go around the Earth（ travelling at the speed of an bullet )
The distance from jupiter to the sun is Jupiter is approximately a little bit five plus astronomical unit
would take about 40 minutes for the four for light to get from the Sun to Jupiter
Comets come from oort clouds, it is made up for frozen gases and particles etc
Voyager 1 lefted on 5 september 1977
Voyager 2 lefted on 20 august 1977
Sedna is a dwarf planet in the outermost reaches of the inner Solar System, orbiting the Sun beyond the orbit of Neptune
Voyager is travelling at 61,000 km per hour
Super high energry electrons and protons are being ejected from the sun
The heliopause is where the velocity and forces of the solar wind are counteracted,that the pressure is so diluted at this point that its counteracted mainly by the helium and hydrogen
The nearest star / The nearest cluster of stars is the alpha centauri
The solar system is roughly the radius of a light year
alpha centauri b
alpha centauri
alpha centauri a
It's 4.2 light years away from earth
All of modern civilization has occurred in the last 10000 years most of recorded is history is around 4000 to 5000 years
Our local neighbourhood of the gaxaly is roughly 1000 light years across
Our local part of the milky way gaxaly is called the orion spur
The andromeda gaxaly is has about a trillion stars
There is a super massive black at the centre of the milky way
The milky way gaxaly is 1000 light years thick
The andromeda igaxaly is 2.5 million light years away from us
The virgo super cluster is 150 million light years across