ASTR terms

Galaxy

Great island of stars help together by gravity and orbiting a common center

Astronomical unit

The average distance between earth and the sun

Planet definition

a large, rounded celestial body that orbits a star, has enough self-gravity to form a nearly round shape, and has cleared its local orbital neighborhood of other debris

Equinox

Equal night and day

Composition of the universe

75 percent is dark energy, 21 percent is dark matter, 4 percent is normal matter

Celestial sphere

Everything in the universe observable from the naked eye

Local sky

What you see in the sky at a point

Meridian

the imaginary line that splits the north and the south

Zenith

The point directly above you at any time

Right ascension

longitude of the stars position west to east relative to the spring equinox

Declination

latitude measuring the stars position of stars north to south

Altitude of the celestial pole equals to your

Latitude

Deferent

In the historical Ptolemaic (Earth-centered) model of the universe, the large main circle or orbit on which a celestial body—or the center of its smaller loop called an epicycle—was thought to travel

Sidereal day vs solar day

A sidereal day is the time it takes for the Earth to complete one full 360-degree rotation relative to distant stars (about 23 hours, 56 minutes, and 4 seconds), while a solar day is the time it takes for the Sun to return to the same position overhead

Mean solar time

a uniform measure of time based on the Earth's rotation relative to a fictitious, average Sun

Insolation

the amount of solar energy that reaches a given area of Earth's surface over a specific period of time

Precessing

a slow, conical change in the orientation of a spinning body's rotational axis

Waxing vs waning

Waxing is when the visible lit surface of the Moon is increasing day by day while waning is when the visible light is decreasing day by day.

Synchronous rotation

happens when an orbiting celestial body's rotational period equals its orbital period, causing the exact same side to permanently face the body it orbits

Geocentric model

places a stationary Earth at the center of the universe, with the Sun, Moon, planets, and stars revolving around it

Retrograde motion

an apparent optical illusion where a planet appears to temporarily reverse its usual eastward path across the night sky and move westward before resuming its normal direction

epicycles

a geometric model used in ancient astronomy to explain the complex, erratic movements of planets, particularly retrograde motion

Copernicus system

a model of the solar system published by Nicolaus Copernicus in 1543 that placed the Sun at the center instead of the Earth

Tycho brahe hypothesis

Hypothesized that the earth was at the center of the universe, while the planets still revolves around the sun

Perihelion and aphelion

Perihelion is when planets is closest to the sun along its orbit while aphelion is the farthest point

Eccentricity

a dimensionless parameter that measures how much an orbit deviates from a perfect circle

Galilean observations

Phases of Venus prove that the planets orbit the sun, disoovered jupiters largest moons, milky was being made up of millions of stars

Speed

speed is a scalar quantity that measures how fast an object moves, defined as the total distance traveled divided by the time it takes

Angluar speed

the rate at which an object rotates or revolves, measuring the angle turned over a specific amount of time

Velocity

a vector quantity that measures the rate and direction of an object's change in position over time

Acceleration

the rate at which an object's velocity changes over time

Scalar vs vector

Both units of measurment while a scalar does not have dirrection while a vector does

Newtons 3 laws

An object at rest stays at rest, and an object in motion stays in motion at a constant speed and in a straight line, unless an external net force acts on it

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass

For every action, there is an equal and opposite reaction

Inertia

the natural tendency of an object to resist changes to its state of motion

Mass vs weight

Mass is the amount of matter in an object, while weight is the gravitational force acting on that matter

Four fundamental forces of nature

gravity, electromagnetism, the strong nuclear force, and the weak nuclear force

Newtons universal law of gravitation

states that every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers, G M1M2/d2

Conserved quantities

physical properties or mathematical combinations that remain constant over time as a system evolves

Conservation of momentum

the total momentum of an isolated system (where no net external force acts) remains constant over time

Circular velocity

the speed of an object moving along a circular path, dependent of radius

Thermal energy

the total kinetic energy created by the random motion and vibration of atoms and molecules within a system or body of matter

Mass energy

the principle that mass and energy are different manifestations of the same underlying physical entity

Gravitational potential energy

the energy stored in an object because of its position in a gravitational field, usually measured relative to the ground. dependent of hight

Black holes

a region in space with such a massive concentration of matter packed into a tiny volume that its gravity is strong enough that nothing—not even light—can escape

Light

a form of electromagnetic radiation that can be perceived by the human eye

Modes of light and matter interaction

Emission, absorption, transmission ( Transarent objects transmit light and opaque object block light), reflection, scattering

Light Wave

transverse electromagnetic waves made of oscillating electric and magnetic fields that move perpendicular to each other and to the direction of the wave

Photon

a fundamental particle that acts as the basic unit of light and all other forms of electromagnetic radiation

Electromagnetic spectrum

the complete range of all types of electromagnetic radiation, organized by frequency, wavelength, or photon energy

Matter

Anything that takes up space on earth, composed of atoms

Unknown phases of change

Sublimation - solid to gas

Ionization - gas to plasma

Recombination - plasma to gas

What is absorption

When light energy strikes the electrons at the exact right amount to change there energy state, then light get absorbed

Spectrum

the narrow band of electromagnetic radiation that the human eye can see, typically spanning wavelengths from about 380 to 750 nanometers (nm)

Continous, emission, and absorption line spectra

Continuous: Smooth, unbroken rainbow of color with a steady increasing graph. Produces from hot dense sources like rock and liquid

Emissions: Colored emissions lines against a dark background. Atomic fingerprint of specific wavelengths of color. Flat with peaks up

Absorption: Rainbow with dark strips representing a low density cload that passes Infront of the light source. peaks with spikes down

Thermal energy

the total kinetic energy created by the random motion, vibration, and collision of atoms and molecules within a substance

Blackbody function

defines the spectral intensity of electromagnetic radiation emitted by an idealized black body in thermal equilibrium at a given temperature

2 laws of black body radiation

§  Peak wavelength is inversely proportional to temperature

§  The hotter an object is, the more energy it emits - flux

Flux

A measure of the total electric or magnetic field passing through a given surface area

Variables of brightness

Brightness is related to temperature, size of object and distance

Chemical fingerprint

a unique pattern of bright lines, dark bands, or wave shifts produced when light interacts with the specific energy levels or molecular vibrations of an element or compound

How to interpret a spectrum

o   First, we want to consider the peaks, which shows the sources of light

§  When there are 2 bumps, that means there is a reflection

o   Second we look at absorption lines shown by the squiggly lines within the spectrum

o   We piece together color, species, features of invisible color

Dopler effect

the apparent change in the frequency or wavelength of a wave caused by the relative motion between the wave's source and its observer

Redshifted vs blueshifted

Redshifted: Stretches out to longer wavelength describing when an object is moving away: positive

Blueshifted: Squishes to shorter wavelengths describing when an object is moving closer: negetive

Radial velocity

the speed at which an object moves toward or away from an observer along the line of sight