# Difference between revisions of "Solar System"

## Event Overview

This event will address the Sun, planets and their satellites, comets, asteroids, the Oort Cloud, the Kuiper Belt, meteoroids, meteorites, and meteors.

For this event be sure to acquire a glossary containing many astronomical terms, a list of famous astronomers and their accomplishments, a table of planetary facts (mass, volume, year length, etc.), detailed diagrams of the sun and solar features, and astronomy formulas.

## Origins of the Solar System

The Solar system was formed about 4.57 billion years ago in a nebula, the center of which was the protosun. Surrounding it were the materials that would be the planets, planetesimals. When the Nebula was sent into a spinning motion (possibly by a large star), the heavier, rocky materials gravitated to the center, and the lighter gaseous materials fell to the outer solar system. In the inner solar system, the small planetesimals continued to gather more material becoming the 4 rocky terrestrial planets (Mercury, Venus, Earth, and Mars). In the outer solar system the rocky materials gathered to form planets, but the lighter gas materials were attracted by the gravity of the cores to form the Jovian planets(Jupiter, Saturn, Uranus, and Neptune). One group of planetesimals that never formed a planet was between Mars and Jupiter. They formed the asteroid belt. The leftover materials on the far edges of the solar system that did not form planets formed the Oort Cloud and Kuiper (kai-per) belt. These two bodies are the source of many comets, the dwarf planets Pluto, Ceres, Eris, Haumea, and Makemake, and the questionable planet Sedna.

## Bodies of the Solar System

(Please note that all of the largest/smallest classifications of the planets are NOT including Pluto! (Which technically isn't really a planet anymore.))

### The Sun

Diameter 1,392,000 km 1.989 1030 kg 3.846 1033 erg/s

The Sun is the largest body in our solar system, and contains 99% of the mass. It is made up of layers, starting from the outside(with Temperatures), Corona(1,000,000 C),Photosphere(6,000 C),Convection Zone(1,000,000 C),Radiative Zone(2,000,000 C),and the Core(15,000,000 C).It produces heat from the fusion of hydrogen atoms. The heat is transferred by the process of convection, through the radiative and the convective zone, where it is radiated out through the photosphere and corona to the planets in the form of rays.This site should contain the solar features that I have not listed here: [1]

### Inner Planets

#### Mercury

is the smallest planet with a radius of 2439 km and the planet closest to the sun at a distance of 57.9 million kilometers. Its year is 88 earth days long, and its day is 59 earth days long. The Surface gravity of mercury is 1/3 of Earth's, so it cannot hold on to an atmosphere. Therefore its surface is scarred with the craters of meteors that would have broken up if it had an atmosphere. The surface temperatures at day and at night are very different, the day temp is 227 C and the night temp is -173 C. It's most noticeable feature is the largest impact crater on its surface, the Caloris basin.

#### Venus

is the 2nd smallest planet in the solar system with a radius of 6051 km, and the 2nd closest to the sun at a distance of 108.2 million kilometers. It is the only planet whose day is longer than its year. Its day is 243 Earth days, and its year is 225 Earth days. It was often called Earth's sister plane because of its close proximity to Earth, and because of its similar diameter and mass. People even thought it could hold life!, but sadly people discovered that the greenhouse effect on Venus raised the surface temp to the highest in the Solar System.

#### Earth

is the third planet from the Sun, and the fifth largest at a radius of 6378 km. It is the only planet in the universe known to support (supposedly) intelligent life. We use it as a basis for many measurements of planets and other things in the solar system (ex. the AU, the average distance between the Earth and the Sun, 93,000,000 miles or 149,600,000 km). The year is equal to 365.256 Earth days, and its day is 1 earth day (But you already knew that).

Moon

Earth's lone moon is aptly called the Moon. It has a radius of 1737 km, making it the fifth-largest moon in the solar system. It is the only object in space that humans have set foot on. Its orbit takes about 27 days, and its rotation takes approximately the same time, resulting in the fact that only one side of the Moon is ever visible to one on Earth.

#### Mars

the fourth planet from the Sun at a distance of 227,392,000 km, is often called the Red Planet, because the large quantities of iron oxide in its soil. The Romans saw it as blood, so they named it for their god of war, Mars. It is the third smallest planet, with a radius of 3397 km. It has a day length of about 25 hours, and a year equal to 687 Earth days. It has been suggested that Mars may hold intelligent life, but it hasn't been proven.

### Outer Planets

#### Jupiter

is the fifth planet from the sun at a distance of 778.3 million km, and the largest with a radius of 71,492 km. Jupiter holds most of the non-solar mass in the solar system. It gives off more energy than it receives from the sun, so it is believed that Jupiter is a failed star, that it could have formed a star, but wasn't under the right conditions. Contrary to popular belief, Jupiter has three small rings around it, made of tiny particles. Its day is the shortest in the solar system at about 10 hours, and its year is equal to 12 earth years. It has an atmosphere composed of hydrogen and helium. The outer layer is the thin visible cloud bands that we see this is also the zone that contains the circular storm known as the Great Red Spot. This is followed by a thick layer of liquid hydrogen. Beneath that is a nearly same size level of liquid hydrogen that, because of the pressure, behaves like a metal. Then beneath that is an iron-silicate core.

#### Uranus

(pronounced your-uhn-us, not: your-anus) is the 3rd largest planet (25,560 km radius), and the seventh from the sun (2.87 billion km away). It was the first planet discovered after prehistoric times, because it is so far away from Earth. It was discovered by William Herschel. Uranus is known for having its axis of rotation parallel to its plane of orbit. Its 9-ring ring system is also parallel to its plane of orbit. These rings are different from those of Jupiter and Saturn, because they are more like hoops than rings of particles, and they have large gaps between them. Its day is about 18 hours long, and its year is 84 Earth years long. Its outer atmosphere is composed of hydrogen, helium, and methane, which gives it its blue green color. Beneath the outer layer is a layer of high pressure solid water, methane, and ammonia. Then, beneath that layer is a ball of rocky material that is very similar to Earth, but its surface is distorted by the dense inner ocean of water and methane.

#### Neptune

the 8th planet from the sun, at a distance of 4.479 billion km, and the 4th largest at a radius of 24,765 km was discovered in 1846 after calculations in Uranus's orbit revealed that its motions were disturbed by a more distant planet. Its day is about 19 hours, and its year is 165 Earth years. The outer third of Neptune is made of hydrogen, helium, water, and methane, which, as on Uranus gives it a blue tint. The inner two thirds are made of molten rock, liquid water, liquid ammonia, and methane. Neptune's most apparent feature is a storm similar to the Great Red Spot, The Great Dark Spot.

### Dwarf Planets

#### Ceres

The largest object in the Asteroid Belt, containing 30% of its mass. When it was discovered in the early 1800s, Ceres was considered a planet, but was reclassified as an asteroid 50 years later. Since 2006, it has been considered a dwarf planet. Ceres orbits the Sun once every 4.6 Earth years and its day is about 9 hours.

#### Haumea

An "egg-shaped" dwarf planet in the Kuiper belt. The odd shape is believed to come from a high rotational speed, which flattens the poles and creates a bulge around the equator. Haumea has a year of about 283 earth years. It also has two moons, Hi'iaka and Namaka.

#### Makemake

Makemake has no moons, making it unique among the larger Kuiper Belt objects. It orbits the sun every 310 years.

#### Eris

Eris is in the scattered disc, a region beyond the Kuiper Belt. Since Eris is larger than Pluto, its discovery led the IAU (International Astronomical Union) to define "planet" and reclassify Pluto as a dwarf planet. Its only satellite is Dysomnia.

## Newton's Laws of Motion and Gravitational Attraction

#### Laws of motion

1. An object at rest stays at rest unless acted on by an outside force. An object in motion stays in motion unless acted on by an outside force.

2. F=ma. Force equals mass times acceleration.

3. For every action, there is an equal and opposite reaction.

#### Law of Gravitational Attraction

Every object attracts every other object with a force proportional to the product of their masses and inversely proportional to the square of their distance.

${\displaystyle F=G{\frac {m_{1}m_{2}}{r^{2}}}}$

F is the magnitude of the gravitational force between the two point masses,

G is the gravitational constant,

m1 is the mass of the first point mass,

m2 is the mass of the second point mass, and

r is the distance between the two point masses.

## Kepler's Laws of Planetary Motion

1. The orbit of every planet is an ellipse with the sun at a focus. 2. A line joining a planet and the sun sweeps out equal areas during equal intervals of time. 3. The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.