| |
|
|
size(m)
|
| |
cosmos
The cosmos is postulated by
some astronomers as a big balloon without boundaries,
with stars and galaxies scattered on the surface.
|
|
1025
|
| |
clusters
of galaxies
Galaxies are held together
by gravity to form clusters of galaxies.
|
1023
|
| |
the Milky
Way
The Milky Way is a typical
spiral galaxy. An average galaxy contains a hundred
billion stars.
|
1021
|
| |
a million
stars
A million stars are held together
by gravity to form a giant cluster.
|
1019
|
| |
the nearest
star
Alpha Centauri in the constellation
of Centaurus is just 4.3 light years from our Sun.
|
1017
|
| |
distant
comets
Astronomers believe that comets
originate from the Oort Cloud which is located 5,000
to 100,000 astronomical units from the Sun.
|
1015
|
| |
the Solar
System and planets
Pluto, the remotest planet
in the Solar System currently known, is about 80 astronomical
units away from the Sun.
|
1013
|
| |
distance:
Venus-Earth-Mars
Venus and Mars are the two
planets closest to the Earth.
|
1011
|
| |
lunar orbit
Light needs 2.6 seconds for
a round trip from the Earth to the Moon.
|
109
|
| |
Earth
Light can travel 7.5 times
around the Earth's equator
in one second.
|
107
|
| |
landscape
Grand Canyon, the longest
canyon on Earth, extends more than 110,000 metres.
|
105
|
| |
ocean trench
Marianas Trench, the world's
deepest ocean trench, is about 10,000 metres deep.
|
103
|
| |
satellite
Satellite antennae with sizes
ranging from several to a few dozens metres are used
for receiving and transmitting radio waves.
|
101
|
| |
embryo
A fertilized human egg in
the first eight weeks is referred to as an embryo, afterwards
it is called a fetus.
|
10-1
|
| |
synapsis
microchip
A synapse serves as a linkage
between neurons or nerve cells.
|
10-3
|
| |
cell
Cells are the basic building
blocks of life. They can be classified as nucleated
and non-nucleated.
|
10-5
|
| |
DNA
In the form of a double helix,
DNA contains the genetic blueprint of an organism.
|
10-7
|
| |
molecules
Matter is made up of molecules
that are in turn composed of atoms.
|
10-9
|
| |
atoms
An element is made up of the
same kind of atoms. An atom contains a nucleus with
electrons orbiting around it. Up to now, 112 elements
have been discovered.
|
10-11
|
| |
atomic nucleus
Composed of protons and neutrons,
the atomic nucleus accounts for more than 99% of the
atom's mass.
|
10-13
|
| |
quarks
Protons and neutrons are made
up of quarks which are by far the smallest entities
identifiable in the laboratory.
|
10-15
|
