Solar System

Newton's First Law

An object remains at rest or in uniform motion unless acted upon by an external force.

Newton's Second Law

Expressed as F = ma, meaning force equals mass times acceleration.

Newton's Third Law

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

Newton's Law of Universal Gravitation

F = G(M₁M₂) / r², describing the gravitational force between two masses separated by distance r.

Kepler's First Law

Planets move in elliptical orbits with the Sun at one focus.

Kepler's Second Law

An imaginary line from the Sun to a planet sweeps equal areas in equal times.

Kepler's Third Law

T² ∝ a³, where T is the orbital period and a is the semi-major axis.

Doppler Effect

Explains how the wavelength of light or sound changes due to motion.

Energy in planetary systems

Mainly kinetic (motion) and potential (position in a gravitational field).

Momentum

Given by p = mv (mass × velocity) and is conserved unless an external force acts.

Force

Any push or pull that changes an object's motion.

Wavelength (λ)

The distance between wave peaks, linked to frequency (ν) and energy (E) via c = λν.

Electromagnetic spectrum

Ranges from gamma rays to radio waves, with specific applications for each type.

Wien's Law

λ_max = b / T, showing that hotter objects emit at shorter wavelengths.

Stefan-Boltzmann Law

E = σT⁴, stating that total energy emitted per unit area increases with the fourth power of temperature.

Spectroscopy

Uses unique spectral lines to identify elements and molecules.

Core accretion

Explains that planets form when dust and ice particles in a protoplanetary disk stick together.

Disk instability

Suggests that parts of the gas disk collapse directly under their own gravity to form giant planets.

Minimum Mass Solar Nebula Model

Helps estimate how much material was needed to form all planets.

Planetary migration

Described by the Nice Model, explains how Jupiter and Saturn's movements reshaped the outer Solar System.

Exoplanets

Planets orbiting stars outside our Solar System.

Hot Jupiters

Gas giants orbiting very close to their stars.

Super-Earths

Rocky planets larger than Earth.

Mini-Neptunes

Smaller gas or ice planets.

Transit Method

A method where a planet passing in front of its star causes a periodic dimming of starlight, revealing the planet's size and orbital period.

Radial Velocity (Doppler) Method

Detects a star's wobble caused by a planet's gravitational pull, revealing planet mass and orbit.

Direct Imaging

Captures actual pictures of planets by blocking star light, best for large, distant planets.

Gravitational Microlensing

Uses light bending from gravity to detect hidden planets.

Exoplanet Atmospheres

Studied by analyzing starlight passing through them during transits, revealing chemical compositions such as water vapor, carbon dioxide, and methane.

Habitable Zone

The region where liquid water could exist, with promising systems including TRAPPIST-1 and Proxima Centauri b.

Extreme Mass Loss

Can transform gas giants into rocky cores, producing hot super-Earths close to their stars.

51 Pegasi b

The first exoplanet discovered around a Sun-like star.

HD 209458 b

The first exoplanet with an atmosphere detected.

Beta Pictoris b

An exoplanet that has been directly imaged.

HL Tauri

A system with planet-forming disks.

Transit Data

Allows scientists to determine radius, orbital period, and distance from the star.

Radial Velocity Data

Measures mass through Doppler shifts in stellar spectra.

Core Accretion Model

States that gas giants form when rocky or icy cores become massive enough to capture large amounts of gas.

Disk Instability Model

Suggests that some gas giants form when parts of the gas disk collapse directly under gravity.

Nice Model

Explains how Jupiter and Saturn's movement reshaped the outer Solar System.

Kilometers (km)

Commonly used for distances within the solar system.

Astronomical Units (AU)

1 AU is the average distance from the Earth to the Sun, approximately 149.6 million km.

Light-years (ly)

Used for interstellar distances; 1 light-year is about 9.46 trillion km.

Kilograms (kg)

Standard metric unit for mass.

Solar Mass (M☉)

A unit of mass used to describe the mass of stars.

Square kilometers (km²)

Used for surface area measurements.

Cubic kilometers (km³)

Used for the volume of planets and moons.

Kelvin (K)

Absolute temperature scale used in scientific contexts.

Seconds (s)

Basic unit of time.

Planet Types

Terrestrial planets have metallic cores, rocky mantles, and solid crusts.

Gas Giants

Composed mainly of hydrogen and helium, with small rocky or metallic cores.

Ice Giants

Have larger proportions of ices such as water, methane, and ammonia.

Density

Used to determine composition: ρ = m / V.

High densities

Indicate rocky/metallic planets (~5.5 g/cm³ like Earth).

Low densities

Indicate mostly gas or ice (~1-2 g/cm³ like Jupiter/Saturn).

Mass loss

Occurs from solar wind and radiation, shaping planets' atmospheres.

Olympus Mons

Tallest volcano in the Solar System, located on Mars.

Terrestrial planets

Formed close to the Sun where it was too hot for gases to condense.

Mercury's atmosphere

Lost most of its atmosphere due to mass loss.

Mars's atmosphere

Lost much of its CO₂ over time.

Jupiter's Europa

Has a subsurface ocean.

Saturn's Titan

Has liquid methane lakes.

Asteroids

Leftover rocky or metallic bodies from planet formation.

Ceres

A dwarf planet located in the asteroid belt.

Comets

Icy bodies from the Kuiper Belt or Oort Cloud, forming tails near the Sun.

Meteoroids

Small rocky fragments that become meteors when entering Earth's atmosphere.

Kuiper Belt

Region beyond Neptune containing icy bodies and dwarf planets.

Oort Cloud

A spherical shell of icy objects thought to be the source of long-period comets.

Density equation

p=3m/(4/3)3.14159r^3.

Scientific Notation

Often used for large numbers, e.g., the mass of Jupiter is about 1.898 x 10²⁷ kg.

Frost line

Marks the distance in a protoplanetary disk where volatile compounds freeze into ice.

BepiColombo

Mission to study Mercury's composition, magnetic field, and atmosphere.

Galileo

Mission to study Jupiter and its moons, especially Europa and Ganymede.

Juno

Mission to study Jupiter's atmosphere, magnetic field, and interior structure.

Cassini

Mission that explored Saturn, its rings, and moons, and found liquid methane lakes on Titan.

Voyager 2

The only spacecraft to visit Jupiter, Saturn, Uranus, and Neptune.

New Horizons

Mission that studied Pluto's surface and sent detailed images of Pluto in 2015.

Dawn

First spacecraft to orbit two different celestial bodies, studying Vesta and Ceres.

Lunar Reconnaissance Orbiter (LRO)

Mapped the Moon's surface in detail to prepare for future human missions.

Deep Impact

Mission that crashed a probe into Comet Tempel 1 to study its composition.

ALMA

Telescope designed to study cold regions of space, like star-forming clouds.

Hubble Space Telescope (HST)

Observes galaxies, stars, and nebulae in visible and ultraviolet light.

James Webb Space Telescope (JWST)

100x more powerful than Hubble, studies the first galaxies and exoplanets.