Material in the Solar System
What are some of the facts about the solar system? Order, size, distance
from the Sun, composition, moons etc.
What are the interesting features about the Solar System?
What are the physical properties about the Solar System?
How do planets form?
How does the solar system form?
What are the theories regarding the Solar System?
The solar system consists of the Sun, with 9 planets around it.
The planets in order from
the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune,
and Pluto as shown above. This diagram is from
The information on solar system is provided by NASA, which also provides the
Solar System Simulator that
alows you to see all planets from any planet of the solar system.
The Solar System
It was, and still is, natural for one to consider oneself the center
of everything. Thus, people have always considered Earth the center
of universe, with the Sun revolving around it. At the dawn of
civilization, when the society was controlled by a few powerful figures,
those spoke of the Earth not being the center would be executed,
because spreading information different from the authorities directly
threatened their power to control people. Thus, only scholar with
courage would speak out for the truth. About 250 BC, Aristarchus
of Samos placed the sun at the center of the solar system, but his
call was mostly ignored.
After having spent a life time observing the movements of stars and
planets, Copernicus (1473 - 1543) realized that the earth revolved
around the sun, a fact contradicting his Church's view. He carefully
recorded his observation, plotted his diagrams, made his conclusion,
and arranged the publication of his book not long before his death.
His prudent work convinced many astronomers, including Galileo
(1564 - 1642), to examine the solar system closely. Due to the
Copernican revolution, the study of astronomy flourished. The results
are summarized in a table form as below.
||No. of satellites
||Distance from Sun
||Surface temperature /K
Many (about 1,600) asteroids in the region between mars and Saturn,
mostly concentrated at 2.8 AU from the sun, and their diameters range
from 800 to a few km.
Masses, equatorial radii, and distances from the Sun are compared with those
of the Earth. Thus, these values of the Earth are given as unity. The mean
distance between the Sun and Earth is usually called an Astronomical Unit
(AU), which is 149,597,870.7 km (one hundred fifty million kilometers),
4.3 light minutes, or 499.0 light seconds.
Recent observation showed that Jupiter, Saturn, Uranus, and Neptune
all have rings, and they all have more satellites than indicated here,
but we don't have the exact numbers.
Some interesting features about the planets in our solar system are given below:
We have no knowledge about other solar system as we do to our
Nine major planets and more than 1600 minor planets (asteroids) have been
identified. They revolve around the sun, all in the same direction.
All the planes containing the orbits of the planets lie within 9o
of each other, except that of the Pluto, whose plane tilts 19o
with respect to the mean. In other words, all but one of the planets revolve
around the sun almost on the same plane. All the orbits are almost circular.
The planet distances from the sun follow the Titius-Bode rule rather well;
0.4, 0.4+3, 4+3*2, 4+3*22 ... , etc. for Mercury, Venus, Earth,
Mars, Minor planets, ... etc., in that order.
Nearly all (99%) the mass of the solar system is in the sun, but most of
the angular momentum is contained in the planets.
Abundant chemical elements in the inner planets are Fe, O, Si, Mg, Ni, and
N but the abundant elements of the outer planets are H, O, N, C, and Ne.
There are two types of satellites. The regular satellites circulate around
the planets in the equatorial planes of the planets, and all in the same
direction, whereas the irregular ones revolve in orbits not contained in
the equatorial plane.
The compositions of gases in the atmospheres on Mercury, Venus, Earth,
and Mars are very different. Mercury surface temperature is high, and
its atmosphere has 43% each of He and N, and about 15% O and H. The gas
consists of mostly mono-atomic molecules due to the high temperature.
On Venus and Mars, CO2 constitute about 96% of all gases.
The atmosphere on Earth consists of 78.8% N2 and 20.95%
O2. The amount of water in the earth atmosphere varies
according to altitude and zones.
The distance from the Sun to the nearest star is 60,000 times the
distance between the Sun and Pluto.
The term planet was derived from Greek, meaning wanderer. There are
three theories concerning the formation of the planets in the solar system,
and none accounts for all facts. Since we know of no other solar system,
the answer as to how planets form remains to be debated. Here are some
Materials from the planets came from the explosion of the nebula around
the sun, no other materials are involved.
The companion star of the sun underwent a red giant stage, and collided
with another star flew by the companion star of the Sun. The debris from
the collision flew by the sun, and the gravitational attraction converted
them into planets.
Materials were gathered from flying debris in space, and they collapsed
into planets due to their own gravitational force.
nebular hypothesis suggests the formation of the entire Solar System
is due to the collection of diffuse gas of previous nebula explosion.
Confidence Building Questions