Solar System

Overview

The Solar System event for the 25-26 season covers objects in the solar system and extrasolar systems as well as general principals. The specific topic for this season is planet formation and evolution in and beyond our solar system.

Objects and their Significant Features

The objects for the current season are Mercury, Jupiter, Saturn, Uranus, Neptune, Pluto, Ceres, the Moon, Triton, 25143 Itokawa, Tempel 1, and 486968 Arrokoth. Competitors are also expected to know these extrasolar systems: Beta Pictoris, HL Tauri, 51 Pegasi, and HD 209458.

For each planet/exoplanet covered in the rules, you are expected to be able to do these things:

1. Identify the object based on a provided image
2. Know the prominent features of the object (storms, landforms, etc.)
3. Know the basic composition of the object (atmosphere, surface, interior)

Planet Formation

There are two main theories that are accepted as how planets form.

Core Accretion

Core accretion is where tiny dust particles collide together, joining into one combined objects. They get bigger and bigger, soon becoming planetissimals, which are hundreds of kilometers wide, and those collide together to eventually form a planet. At a point, a planet gets big enough to start accreting gas. This is where the formation of a rocky planet ends, when it gets some sort of a small atmosphere. In core accretion, for a gas giant to form a planet must reach a critical core mass in which the rate in which it accretes gas is more than the rate of solid accretion.

Disk Instability

Disk instability is when a disk that is too wide and thin to support itself collapses onto itself at a certain point quite fast, quickly forming a (usually very large) gas giant. The equation used to see if a disk is stable or not is the Toomre's Stability Criterion.

Small Solar System Bodies

Comets

A comet is a celestial object consisting of a nucleus of ice and dust and, when near the sun, a “tail” of gas and dust particles pointing away from the sun.

Asteroids

An asteroid is a small rocky body orbiting the sun. Large numbers of these, ranging in size from nearly 600 miles (1,000 km) across (Ceres) to dust particles, are found (as the asteroid belt ) especially between the orbits of Mars and Jupiter, though some have more eccentric orbits, and a few pass close to the earth or enter the atmosphere as meteors.

Centaurs

Centaurs are icy planetesimals located between Jupiter and Neptune. They cross the orbits of one or more of the giant planets in their journey around the Sun, and interactions with these outer planets cause the orbits of Centaurs to be inherently unstable.

Exoplanet Detection Methods

Radial Velocity Method

The radial-velocity method for detecting exoplanets relies on the fact that a star does not remain completely stationary when it is orbited by a planet. The star moves, ever so slightly, in a small circle or ellipse, responding to the gravitational tug of its smaller companion.

Transit Method

Most known exoplanets have been discovered using the transit method. A transit occurs when a planet passes between a star and its observer. Transits within our solar system can be observed from Earth when Venus or Mercury travel between us and the Sun.

Direct Imaging

Direct Imaging is... just taking a picture of the object.

Mathematical Concepts

Major Mathematical Concepts and Equations that you should study are as follows:

1. Kepler's Laws
2. Newton's Laws
3. Escape Velocity
4. Surface Gravity
5. Density
6. Stefan-Boltzmann
7. Wien's Law
8. Planck's Law
9. Transit Depth
10. Doppler Shift