Copy of `Kids Know It - Astronomy terms`

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Kids Know It - Astronomy terms Category: Sciences > Astronomy Date & country: 15/02/2017, USA Words: 140

Zenith
Point directly above your head in the night sky.

Variable stars
Stars which fluctuate in brightness.

Umbra
The dark inner part of a sunspot, or shadow.

Troposphere
The lowest part of the Earth's atmosphere.

Trojans asteroids
Asteroids that circle the Sun following Jupiter's orbit.

Thermocouple
An instrument used for measuring very small quantities of heat.

Time dilation
The idea that as you approach the speed of light time slows down and mass increases.

Terminator
The line between day and night on any celestial object.

Syzygy
The position of the Moon in its orbit when at new or full phase.

Synodic Period
The time it takes an object in space to reappear at the same point in relation to two other objects, e.g., the Earth and Sun.

Sun spots
Dark patches on the Sun's surface.

Sundial
Ancient instrument used to tell time.

Superior planets
The planets which lie further from the Sun than the Earth.

Supernova
A super bright explosion of a star. A supernova can produce the same amount of energy in one second as an entire galaxy.

Synchronous satellite
An artificial satellite which moves around the Earth at the same speed that the Earth rotates, so that it is always above the same part of Earth.

Stratosphere
Level of the Earth's atmosphere from about 11-64 kilometers (7-11 miles) above sea level.

Spicules
Jets up to 16,000 kilometers in diameter in the Sun's atmosphere.

Star
A self-luminous object that shines through the release of energy produced by nuclear reactions at its core.

Sidereal Period
The period of time that it takes an object in space to complete one full orbit in relation to the stars.

Solar System
The system of planets and other objects orbiting the star Sol, which happens to be our Sun.

Solar wind
A steady flow of particles streaming out from the Sun in all directions.

Solstice
22 June, and 22 December. Time of the year when the day is either shortest, or longest depending on where you are.

Scintillation
Twinkling of stars. Due to the Earth's atmosphere.

Seeing
The condition of the Earth's atmosphere at a particular time. If the sky is clear astronomers say there is good seeing.

Selenography
The study of the Moon's surface.

Seyfert galaxies
Galaxies with small bright centers. Many Seyfert galaxies are good sources of radio waves.

Shooting star
A light in the atmosphere caused by a meteor falling towards the Earth.

Revolve
When something is moving in a circle around another object, such as the way the Moon Circles the Earth, it is said to revolve around that object.

Rotate
When an object spins it is said to be rotating.

Saros cycle
A period of 18 years 11.3 days in which eclipses repeat themselves.

Satellite
A small object orbiting a larger one. There are many electronic objects that orbit the Earth.

Red shift
When an object is traveling away from the Earth, the light from this object is stretched out, making it look redder.

Radio galaxies
Galaxies which are extremely powerful emitters of radio radiation.

Radiant
The area in the sky where during a meteor shower the meteors appear to radiate from.

Quasar
A very distant, immensely bright object.

Precession
The Earth behaves like a spinning top. Its poles are spinning in circles causing the poles to point in different directions over time. It takes 25,800 years for the Earth to complete one precession.

Proper motion
The motion of the stars across the sky as seen from Earth. Closer stars have a higher proper motion than more distant ones, just as in your car closer objects such as road signs seem to move faster than distant mountains and trees.

Proton
The center of an atom is made up of one or more protons. It has a positive charge.

Perturbations
The disturbances in the orbit of a celestial object caused by the gravitational pull of another object.

Photosphere
The bright surface of the Sun.

Phases
The apparent change in the shape of the Moon, Mercury, and Venus due to how much of the sunlit side is facing the Earth.

Planet
An object moving around a star.

Planetary nebula
A nebula of gas surrounding a star.

Perihelion
When an object which revolves around the Sun is at the closest point it gets to the Sun.

Parallax
The shift of an object when it is viewed from two different places. For example if you close one eye and look at your thumb nail, and then switch eyes, you will see everything in the background move back and forth. Scientists use this to measure the distance to stars.

Parsec
3.26 light years

Penumbra
The lighter part of a shadow found on the shadow's edge.

Periastron
When two stars that orbit each other are at their closest point.

Perigee
The point in an object's orbit around the Earth when it is closest to the Earth.

Ozone
An area in the Earth's upper atmosphere which absorbs many of the lethal radiations coming from space.

Occultation
The covering up of one celestial body by another.

Opposition
When a planet is exactly opposite the Sun so that the Earth is between them.

Orbit
The path one object takes around another.

Neutrino
A very small particle with no mass or charge.

Neutron star
The remnants of a dead star. They are incredibly compact and spin very quickly, some spin 100 times a second.

Nova
A star which suddenly flares up to many times its original brightness before fading again.

Oblate Spheroid
A planet that is not perfectly round because it is wider in the middle and shorter from top to bottom.

Nebula
A cloud of gas and dust.

Nadir
That point on the celestial sphere directly below the observer.

Multiple star
A group of stars that orbit each other.

Minor planet
Asteroid

Molecule
A group of atoms linked together.

Meteor
A shooting star, observed when a particle of dust enters into the Earth's atmosphere.

Meteorite
An object from Outer Space, such as a rock, that falls into the Earth and lands on its surface.

Meteoroids
Any small object in Outer Space, such as dust or a rock.

Micrometeorites
An extremely small object. They are so small that when they hit the Earth's atmosphere they do not create a shooting star effect.

Mass
How much matter an object contains. It is not the same as weight, although an object's mass does help determine how much it will weigh.

Limb
The edge of any object in Outer Space. The edge of the Moon for example.

Local Group
A group of around two dozen galaxies. It is the group to which our galaxy belongs.

Lunation
Period between new moons. 29 days 12 hours 44 minutes.

Magnetosphere
Region around an object where the influence of the object's magnetic field can be felt.

Kirkwood gaps
Regions in the asteroid belt where almost no asteroids can be found. This is due to the fact that the giant planet Jupiter changes the orbits of any object which enters these areas.

Light Year
The distance which a ray of light would travel in one year. This is about 6,000,000,000,000 (6 trillion) miles.

Hubble Constant
The relationship between the distance of an object and the speed at which it is traveling away from us. The further away an object is the faster away from us it is traveling.

Inferior planets
Mercury and Venus which lie closer to the Sun than the Earth are called inferior planets.

Ionosphere
A region of the Earth's atmosphere.

Kelvin
A measurement of temperature often used in astronomy. 0 degrees Kelvin equals -273 degrees Celsius and -459.4 degrees Fahrenheit.

Kepler's Laws of Planetary Motion
1. The planets move in elliptical orbits with the Sun at one focus. 2. An imaginary line joining the center of a planet to the center of the Sun sweeps the same amount of space all the time. 3. The time it takes a planet to orbit the Sun is related to how far away from the Sun an object is.

Geophysics
Study of the Earth using Physics.

Gibbous
When the Moon is more than half full, but less than completely full.

Hertzsprung-Russell Diagram
A diagram which helps scientists understand different kinds of stars. click here to learn more.

HI region
Cloud of neutral hydrogen.

HII region
Cloud of ionized hydrogen.

Exosphere
The outermost part of the Earth's atmosphere.

Flares
Beautiful eruptions in the outer part of the Sun's atmosphere.

Galaxy
group of stars, gas and dust held together by gravity.

Gamma ray
Extremely short-wavelength and energetic electromagnetic radiation.

Geocentric
Simply means the Earth in the Center. People used to believe the Universe was geocentric, or that the Earth was in the center of the Universe.

Escape velocity
The speed an object must have in order to escape from another object's gravity.

Electron
Negative particle which orbits an atom.

Element
Substance which cannot be broken down any further. There are 92 known elements.

Equinox
March 21st and September 22nd. Twice a year when the day and night are the same amount of time all around the world.

Ecliptic
The path the Sun, Moon, and planets all follow in the sky.

Ecosphere
The area around a star where it is just the right temperature for life to exist.

Earthshine
faint glow of the moon when the side facing Earth is dark. Caused by light reflecting off the Earth.

Eclipse
When our view of one object in the sky is blocked by either another object or the Earth's shadow.

Diurnal motion
The apparent motion of the sky from East to West caused by the Earth moving from West to East.

Coronagraph
A type of telescope designed to view the Sun's Corona.

Cosmic rays
High-speed particles that reach the Earth from Outer Space.

Cosmology
The study of the universe.