Astronomy Flashcards
What is a star?
A large spherical ball of plasma, undergoing nuclear fusion at its core.
What is a planet?
A large ball of matter which orbits a star.
What is a dwarf planet?
An object that orbits a star but is not large enough or roughly spherical enough to be classed as a planet.
What is a moon?
A natural satellite of a planet or dwarf planet.
What is an asteroid?
An orbiting object which is even smaller than a dwarf planet. They are formed of rock and metals.
What is a Comet?
An object made of dust and ice that forms a ‘tail’ when it gets close to the Sun.
What is a solar system?
A solar system consists of a central star orbited by planets and other matter.
What is an exoplanet?
A planet existing around another star, outside of our solar system.
What is a galaxy?
A large cluster of stars, all orbiting a central gravitational point.
What is the universe?
The Universe is the sum of all matter, energy,
space, and time.
What is an Astronomical Unit?
The average distance from the Sun to Earth
What is a Light-year?
Distance travelled at the speed of light in one year.
What is a constellation?
A pattern of stars on the night sky forming a shape.
How can “North” be found using the stars?
Find the “pointer stars” of Ursa Major (the plough), follow a line from these out of the ‘bowl’ to the next brightest star - Polaris (the north star).
What is the “Speed of Light”?
3x10⁸ ms ⁻¹
How can the number of seconds in 1 year be calculated?
1 x 365.35 x 24 x 60 x 60
Approximately how old is the Universe?
~13.8 Billion years
Approximately how old is our Solar system?
~4.5 Billion years
Which Force causes clouds of dust and gas to collapse to form Stars and star systems?
Gravitational force.
What process occurs in the core of a star, releasing vast amounts of energy
Nuclear Fusion.
What is the shape of the orbit of a Comet?
An ellipse.
What is the shape of orbit of a Planet?
A circle.
What is meant by a Meteoroid?
Any small chucks of rock in space too small to be classed as an asteroid.
What is meant by a Meteor?
A meteoroid that is travelling through the atmosphere. It becomes so hot that it glows brightly and can be vaporised.
Also known as a shooting star.
What is meant by a Meteorite?
A metoroid that has survived its passage through the atmosphere and has impacted the ground.
What is meant by a Meteor shower?
A point in time when the number of meteoroids entering the the atmosphere increases dramatically. Occurs when the Earth passes through the debris of a broken up comet.
What is meant by the “Radiant”?
The point in the night sky where the meteors of a shower all appear to be coming from. Its location within a constellation gives the shower its name.
Why is a crater formed when a meteoroid impacts the ground?
All of its kinetic energy is converted in light heat and sound. This rapid release of energy forms the impact crater.
What factors affect the size of an Impact crater?
- Object size (mass)
- Density of object
- Speed of impact
- Angle of impact
- Material of impacted surface
What is the “Law of reflection”?
For a mirrored surface, the angle of Incidence of a ray of light is equal to the angle of Reflection.
What is meant by “Refraction”?
The process by which a ray of Light changes speed as it moves between materials of different density.
Why is a large objective lens or primary mirror important within a telescope?
The larger the ‘aperture’ of a telescope, the more light it can gather.
What is the purpose of the eyepiece lens or secondary mirror within a telescope?
To magnify the image produced by the telescope.
What does a reflecting telescope use to ‘redirect’ light?
Mirrors
What does a refracting telescope use to ‘redirect’ light?
Lenses
What does a catadioptric telescope use to ‘redirect’ light?
Both lenses and mirrors
