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是advantages and disadvantages of space exploration!!!!
- 1 十年前最愛解答
The solar system consists of the Sun; the eight official planets, at least three "dwarf planets", more than 130 satellites of the planets, a large number of small bodies (the comets and asteroids), and the interplanetary medium. (There are probably also many more planetary satellites that have not yet been discovered.)
The inner solar system contains the Sun, Mercury, Venus, Earth and Mars:
The main asteroid belt (not shown) lies between the orbits of Mars and Jupiter. The planets of the outer solar system are Jupiter, Saturn, Uranus, and Neptune (Pluto is now classified as a dwarf planet)
The first thing to notice is that the solar system is mostly empty space. The planets are very small compared to the space between them. Even the dots on the diagrams above are too big to be in proper scale with respect to the sizes of the orbits.
The orbits of the planets are ellipses with the Sun at one focus, though all except Mercury are very nearly circular. The orbits of the planets are all more or less in the same plane (called the ecliptic and defined by the plane of the Earth's orbit). The ecliptic is inclined only 7 degrees from the plane of the Sun's equator. The above diagrams show the relative sizes of the orbits of the eight planets (plus Pluto) from a perspective somewhat above the ecliptic (hence their non-circular appearance). They all orbit in the same direction (counter-clockwise looking down from above the Sun's north pole); all but Venus, Uranus and Pluto also rotate in that same sense.
(The above diagrams show correct positions for October 1996 as generated by the excellent planetarium program Starry Night; there are also many other similar programs available, some free.)
The above composite shows the eight planets and Pluto with approximately correct relative sizes (see another similar composite and a comparison of the terrestrial planets or Appendix 2 for more).
One way to help visualize the relative sizes in the solar system is to imagine a model in which everything is reduced in size by a factor of a billion. Then the model Earth would be about 1.3 cm in diameter (the size of a grape). The Moon would be about 30 cm (about a foot) from the Earth. The Sun would be 1.5 meters in diameter (about the height of a man) and 150 meters (about a city block) from the Earth. Jupiter would be 15 cm in diameter (the size of a large grapefruit) and 5 blocks away from the Sun. Saturn (the size of an orange) would be 10 blocks away; Uranus and Neptune (lemons) 20 and 30 blocks away. A human on this scale would be the size of an atom but the nearest star would be over 40000 km away.
Not shown in the above illustrations are the numerous smaller bodies that inhabit the solar system: the satellites of the planets; the large number of asteroids (small rocky bodies) orbiting the Sun, mostly between Mars and Jupiter but also elsewhere; the comets (small icy bodies) which come and go from the inner parts of the solar system in highly elongated orbits and at random orientations to the ecliptic; and the many small icy bodies beyond Neptune in the Kuiper Belt. With a few exceptions, the planetary satellites orbit in the same sense as the planets and approximately in the plane of the ecliptic but this is not generally true for comets and asteroids.
The earth has an ozone hole.
The earth will turn hot in 50 years.
The sun will turn into a white dwarf in billions of years.
The universe might collapse in a ' Big Crunch'.
- CharlieLv 51 十年前
We can learning
(EG:Venus and Mercury)
If from the country's point of view.Second countries will be afraid of it.
Becrase vast amounts of money to explore outer space.
So the more money that it is very (to spend more...多到用唔曬-.-")
And than,the most powerful nation is the United States.(E個係事實)
There are a lot of disadvantages
EG:Each will have a large space waste, if unfortunate bridge Earth, it will result in casualties (To be too great!)
This is a single can be killed to Earth!