The Sun

Science 9

An Important Star

• Provides energy for life• Keeps Earth in a steady orbit• It is the closest star to Earth and the brightest

object in the sky• It gets its energy from nuclear fusion• Particles come together to form new substances• This produces heat, light and other forms of

energy

How Old is the Sun?

• The Sun is approximately 5 billion years old

• it should continue to produce energy for another 5 billion years old

• Does this mean that the sun has hit middle age?

A Close Look at the Sun

• Based on data collected from studies of the Sun, the following terms have been used to describe what is happening on the Sun– Solar flare– Photosphere– Solar prominences– Moving gases– Core– Chromosphere– Corona

Characteristics of Other Stars

• There are billions of other stars in the universe• Increasing evidence that there are many stars

that have planets orbiting them• The colours of stars helps to estimate its

temperature – cool glows red, hot glows blue• Spectroscopes are used to help see all the

colours a star emits• They help us determine what elements are

present on a star and in what quantity

Star Light, Star Bright

• Stars can be classified according to their brightness

• Apparent magnitude is the term used to represent brightness of a star from our position on Earth

• Absolute magnitude refers to the actual amount of light given off by a star at a standard distance.– All stars are considered to be the same distance

from Earth when this is calculated

How Does the Sun Measure Up?

• The Sun has the greatest apparent magnitude because it is the closest star to us

• However, its absolute magnitude is only considered to be average