Activity 12

Complete the following text with suitable words from the box. Read the text aloud, in turns.

    Many stars formed millions, if not billions, of years ago. Furthermore, the starlight that reaches our eyes left those (1) ____ starts some time ago-ranging from a few minutes ago (the Sun) to fours years ago (Alpha Centauri, the Sun's nearest star neighbor) to a much longer time ago (objects at the edges of your galaxy).

    We measure these distances in light-years. One light-years is (2) ____ to approximately 6 trillion miles, or the distance light travels in one 365-day earth year. Alpha Centauri, at 25 trillion miles from Earth, is about 4 light-years away. The light we (3) ____ today from the Andromeda Galaxy left it two and a half millions years ago: Andromeda is 2.5 millions times 24 trillion miies away.

    Stars, which are (4) ____ of gas (mostly the gases hydrogen and helium) emit radiation. They create energy by fusing hydrogen and turning (5) ____ into helium in their cores. We see the resulting energy as (6) ____.

    Astronomers classify star (7) ____ their size, temperature, color, and luminosity. Size in this case relates to mass rather than linear measurement, such as diameter. Stars start the same way, but (8) ____ lives play out according to their (9) ____ and mass. The mass of a star determines all of its other (10) ____ including how hot is it, what color it is, and how long it will live. Massive stars are hot and blue, whereas small stars are cool and red.

Adopted from: National Geographic, Answer Book 10,001 Fast Fact about Our World, Washington DC, National Geographic, 2015.

Complete the following statements based on the text in Activity 12.

Alpha Centaury is ____ four light-year away from the Earth.