Page 309 - (DK) I Can’t Believe It! 2

TRUE OR FALSE? 307
Starlight is find out which stars produce the most light by FAST FACTS
Stars produce different amounts of light. We
comparing their luminosity—the energy a star
emits in just one second. The brightest stars THE HOTTEST STARS
millions of years old release more than six million times the light ARE BLUE
of the sun, while the least luminous stars
You might expect the hottest stars
create less than one ten-thousandth.
to be red, and the coolest to be
blue, but in fact it’s the other
way around. Blue stars reach a
Are there more Heat and light temperature of about 72,000°F
(40,000°C), while red stars get
stars in the are produced no hotter than 7,200°F (4,000°C).
sky or grains when hydrogen
of sand turns into helium HOW A STAR DIES DEPENDS ON
gas inside the
on Earth? star’s core. ITS MASS—THE AMOUNT OF
MATERIAL IT IS MADE FROM
Massive stars can blow up, but SUNLIKE RED GIANT PLANETARY
Light from these stars we may not know for thousands of STAR NEBULA
takes 16,000 years to years. We see how the star looked
reach Earth. This cluster when the light left years ago.
is like a beehive swarm MASSIVE STAR RED SUPERGIANT SUPERNOVA
of 10 million stars.
Sunlike stars shine brightly for billions of years.
Late in life, they expand to become a cooler,
brighter star called a red giant. It sheds
its outer layers, called a planetary
nebula. Stars with more than eight
times the sun’s mass last only
a few million years. They become
supergiants, which explode as
supernovas and leave a neutron
star or a black hole behind.

OMEGA
CENTAURI

Ancient stars more than
10 billion years old

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