CIE IGCSE Space Physics Flashcards

Flashcards covering Earth's rotation and orbit, the Solar System components, star life cycles, orbital mechanics, and the Big Bang Theory based on CIE IGCSE Physics notes.

Earth's Axis

An imaginary line passing through the North and South poles, tilted at an angle of $23.5^{\circ}$ from the vertical.

Rotation

The movement of Earth from west to east on its axis, taking about 24 hours to complete one rotation.

Earth's Orbit

The elliptical path the Earth takes around the Sun, which takes approximately 365 days to complete.

Moon

A natural satellite that orbits the Earth, taking about 28 days to complete one orbit and reflecting light from the Sun.

Phases of the Moon

The changes in the appearance of the Moon's illuminated side as seen from Earth as it orbits.

Average Orbital Speed Formula

The equation $v = \frac{2\pi r}{T}$, where $v$ is average orbital speed, $r$ is the average radius of the orbit, and $T$ is the orbital period.

The Sun

The only star in our Solar System, which contains most of its mass and provides light and heat.

Inner Planets

The four planets nearest the Sun (Mercury, Venus, Earth, and Mars) that are characterized as rocky and small.

Outer Planets

The four planets furthest from the Sun (Jupiter, Saturn, Uranus, and Neptune) which are gaseous and large.

Minor Planets

Objects that orbit the Sun including dwarf planets such as Pluto and asteroids found in the asteroid belt.

Accretion Model

The theory of Solar System formation involving the rotation of material in interstellar clouds of gas and dust and the formation of an accretion disc dependent on gravity.

Speed of Electromagnetic Radiation

The constant speed at which radiation from the Sun travels through space, equal to $3.0 \times 10^8\,\text{m/s}$.

Perihelion

The point in an elliptical orbit where a planet is at its closest distance to the Sun.

Aphelion

The point in an elliptical orbit where a planet is at its farthest distance from the Sun.

Eccentricity

A measure used to describe the shape of an orbit; the more eccentric an orbit is, the more oval-shaped it is.

Conservation of Energy in Orbit

The principle that a planet's total energy stays constant, with kinetic energy increasing while potential energy decreases as it moves closer to the Sun.

Nuclear Fusion

The process in the Sun's core where hydrogen nuclei combine to form helium, releasing energy; requires temperatures of about $15 \times 10^6\,\text{kelvin}$.

Galaxies

Huge collections of stars, gas, and dust held together by gravity; our Sun is part of the spiral-shaped Milky Way galaxy.

Light-year

The distance light travels in one year, approximately $9.5 \times 10^{12}\,\text{km}$.

Nebulae

Clouds of gas and dust in space that serve as the birthplaces of stars.

Protostar

A stage in star formation where gravity causes clouds to collapse and heat up before reaching stability.

Hydrostatic Equilibrium

The state of a stable star where the inward force of gravity is balanced by an outward force due to high central temperatures.

Red Giant

A stage where a low-mass star runs out of hydrogen in its core, expands, and cools down.

White Dwarf

A hot, dense star that remains at the center after a red giant sheds its outer layers to form a planetary nebula.

Supernova

The explosion of a high-mass red supergiant that leaves behind a nebula containing new heavier elements and a neutron star or black hole.

Redshift

The stretching of light wavelengths as a star or galaxy moves away, making the light appear more red and indicating the Universe is expanding.

Big Bang Theory

The scientific model stating the Universe began about 13.8 billion years ago from a small, hot, dense region.

Cosmic Microwave Background Radiation (CMBR)

A type of radiation filling all space with a temperature of about $-270^{\circ}\text{C}$, evidence that the Universe was once much hotter and denser.

Hubble Constant ($H_0$)

The ratio of the speed at which a galaxy moves away from us to its distance; the current estimate is $2.2 \times 10^{-18}\,\text{per second}$.

Age of the Universe Estimation

Calculated by the formula $\frac{d}{v} = \frac{1}{H_0}$, resulting in an estimate of about 14 billion years.