Planets drastically vary in their distance from the Sun, period of revolution about the Sun, period of rotatio

Question

i need it for a science project :)

Answer 1

Yes, planets do have varying orbits.

Planets, asteroids, and comets do not revolve on a circular track, instead it is closer to an oval. When an astronomical body orbits a star it does so in a seemingly odd but regular pattern. As the object gets closer to the sun its motion speeds up and the closer it gets the faster the speed is. If the object is in a stable orbit then it will swing past the sun and move out into the solar system. As it does this the object’s speed decreases. At some point the speed that the object is moving is less than that attractive force of the sun. When this happens the object starts to fall toward its sun again. As it falls the speed increases and the object will have enough speed to stay in orbit instead of crashing into the sun (this speed is the objects momentum). The momentum will be enough to keep the object in its orbit and let it move back out into the solar system.

For comets this can be a long time. Halley’s comet has a very regular 75 year orbital period, another words it takes 75 years for the comet to make a complete orbit. There are a lot of comets, asteroids and bits of rock that are lose in our solar system. Most of them fall into regular orbital motions. The Asteroid Belt is the area between Mars and Jupiter and the Ort Cloud is out beyond Uranus. Jupiter is a huge planet (just a little to small to not be a sun in its own right) and it has a large gravitational field. When bits of rock float around in the Asteroid Belt or the Ort Cloud they are chaotic and might knock against each other. If this happens they could be moved to another orbit. If this happens and Jupiter is in the right place then the gravity of Jupiter is enough to pull the rock out of its orbit and send it toward the Sun. Many of these rocks are never seen by man and a large number of them fall into the Sun. The rest, a small number, obtain a stable orbit. They travel around the sun and then move out toward the outer regions of the solar system, where they slow down and fall right back in toward the sun.

When one of these bits of rock has ice on it the ice melts as it gets closer to the Sun and the comet shows its tail. These are the objects that are easy to find. The majority though are only asteroids with no melting ice on them. It is very hard to see them and they can get very close to the Earth before they are detected. We call these asteroids NEO Near Earth Orbiting Asteroids; they are also called Earth Crossing Asteroids. One such asteroid was a large one and turned into the famed Dinosaur Killer. The danger is that if we don’t find more of these NEO asteroids then one may get too close to the Earth and hit it. A rock only a few miles wide is enough to cause worldwide devastation. They are out there, and they will hit the Earth, it is not a question of IF, but WHEN. You only have to look at the moon to see all the asteroids that have hit it. The moon does a very important job of sweeping up some of those NEO objects, and it helps life on the Earth survive. For a long time people didn’t think that there were that many asteroids out there and that we were safe from collisions. The famous amateur astronomer Shoemaker proved that was wrong. Now days he is running a worldwide program of fellow amateur astronomers to try and discover every NEO and catalog it. If enough observations are made then the asteroid’s orbit can be calculated and it can be proved if the asteroid will be a threat to us or not.

The orbit of most objects follows an elliptical plan. An ellipse is a circle that has been elongated so that it has two centers. If you put the Sun at one center then you will have the average orbital plan of most astronomical objects. These orbits can be very complex when other objects are involved. The moons and rings of Saturn and Jupiter illustrate this.

These orbital plans are precise and if all the gravitational attractions are known they can be calculated down to only a few dozen feet. When the Voyager and Pioneer space probes were launched they used a gravitational assist to get enough speed to reach the outer solar system. If you go on a standard elliptical orbital plan and change you speed just a little as the closest point of approach to the object you are orbiting around then you will get a boost of speed. A little energy will be transmitted to the satellite accelerating it. Voyager used this plan to get an orbital boost when it orbited Earth, Venus, the Sun, and the Earth again. Done in the proper fashion it shot those probes out to Jupiter and Saturn. Until last year the two Voyager probes were the fastest man made object in the Universe. The ion propelled Horizon probe is now moving faster on its way to study Pluto (it was launched before Pluto got demoted to a Dwarf Planet).

According to Wikipedia: http://en.wikipedia.org/wiki/Apsis

“In astronomy, an apsis, plural apsides (IPA: /apsɪdɪːz/) is the point of greatest or least distance of the elliptical orbit of an astronomical object from its center of attraction, which is generally the center of mass of the system.
The point of closest approach is called the periapsis or pericentre and the point of farthest excursion is called the apoapsis (Greek από, from, which becomes απ before a vowel, and αφ before rough breathing), apocentre or apapsis (the latter term, although etymologically more correct, is much less used). A straight line drawn through the periapsis and apoapsis is the line of apsides. This is the major axis of the ellipse, the line through the longest part of the ellipse.
Related terms are used to identify the body being orbited. The most common are perigee and apogee, referring to orbits around the Earth, and perihelion and aphelion, referring to orbits around the Sun (Greek ‘ήλιος hēlios sun).”

Check out the graphic to see what I am talking about with orbital paths.
Also read this article: http://en.wikipedia.org/wiki/Orbit

If you look down the page you will see complex and unfamilar formulas. These formulas are calculus (highly advanced math) equations and are used to describe the formula that determines the exact position on the orbital path at any time. They are all based on the simple equation F=ma, but in that case of ellipitical orbits that formula only holds true for the AVERAGE values.

The period of revolution is called a year. A year on Earth is 365.25 days. For other planets the orbital period (or its year) varies with the distance from the sun and the speed that the object is moving at.

This Wikipedia article will help as well: http://en.wikipedia.org/wiki/Elliptic_orbit

The Sun has orbital hot spots called Trojans. Due to the gravational effects of the sun and other bodies some things collect at certain points in space. Think of these points as a dip in the gravitational fabric. This Wikipedia article will help you understand Trojan Points: http://en.wikipedia.org/wiki/Trojan_%28astronomy%29

According to Wikipedia: http://en.wikipedia.org/wiki/Satellite_orbit
“Satellite orbits are always conic sections. That is to say they always form either circles, ellipses, parabolas, or hyperbolas. Since satellite orbits can be hyperbolic which are open-ended orbits, some comets or asteroids form an orbit where their path may come into our solar system and exit never to return. The first space missions to the moon were sent up in hyperbolic orbits so that if there were a system failure, the astronauts would not have been able to return.
Satellites follow specific orbits relating to the gravitational force between the satellite and the object it orbits. These orbits follow Newton’s laws of motion. However, in strong gravitational fields such as around neutron stars and black holes, Einstein's law of general relativity predicts orbits.”

Of those orbits on the ellipses orbit is a stable one. A parabolas orbit will need orbital correction to maintain a stable orbit. This can be done with thrusters on board the spacecraft. A hyperbolas orbit is one that approaches the object it is orbiting and then zooms off into space never to return. If orbital corrections weren’t made to the Apollo spacecraft they would have never returned to Earth.

Answer 2

No they are almost circular in orbit and do nothing like you say. Go to wikipedia and look up planets.

Answer 3

Earth's orbit is nearly circular and its rotation is consistent. I don't know about the other planets.

Answer 4

Try Wikpedia.com