Stars
What is a star?
Spheres of hot gas, mainly hydrogen and helium
What is Light?
Light is a wave of visible energy on the electromagnetic spectrum
What is a hot body?
An object that emits its own light in space
What is the part of the electromagnetic spectrum that we can see?
Visible light
What is the process called that allows stars to create their own light?
Nuclear fusion
How does light travel through space?
Light travels as waves through space
What is a cold body
An object that reflects light from another source, such as the sun
The slowest moving wave in the spectrum is called what?
radio waves
Why do stars appear as small points of light in the night sky, even though many are much larger than Earth.
As stars are incredibly far away from earth it takes time for the light to travel from the star to earth where we can see it
300,000 km/s
Identify two examples of hot bodies and two examples of relatively cold bodies found in space.
Hot bodies = stars, meteors
Cold bodies = planets, satellites, comets
The fastest moving waves in the electromagnetic spectrum is called what?
Gamma rays
The Sun is approximately 150 million kilometres from Earth. Explain why it appears much brighter and larger than most other stars in the night sky.
The sun is relatively close to earth compared to other stars, hence it appears to be brighter and larger.
A star is 20 light-years away from Earth. Explain what this tells us about the light we observe from that star today.
The light we observe from a star 20 light-years away today is actually from that star as it was 20 years ago. This means that the light we see is from the star as it existed 20 years ago, and it has taken 20 years for the light to reach us.
Explain why the Sun is classified as a hot body, while a comet is classified as a cold body
Sun emits its own light through nuclear fusion. Comets when moving reflect the light from stars on its dust and ice as it moves through space
Compare radio waves and gamma rays in terms of wavelength, frequency and energy.
Radio waves = low energy, large wavelength and low frequency
Gamma rays = high energy, small wavelength and high frequency
Explain why stars are visible at night to us on Earth
Stars produce their own light, which travels through space to Earth. They are visible at night when the Sun is below our horizon, and its bright light no longer overwhelms most of the stars in the sky
Explain the difference between luminous objects, such as stars, and non-luminous objects, such as planets
nonluminous objects (planets) = reflect light
A comet travels closer to the Sun during its orbit. Predict what happens to its temperature and explain how this can affect its ice and dust.
The comet will heat up from the temperature of the sun and begin to turn from the solid rock to a gas as it combusts.
Which two sections of the electromagnetic spectrum can penetrate though earth's atmosphere?
Visible light and radio waves