|Which stars are cooler red or blue?|
|Question Date: 2013-05-09|
To answer this question, we should first try to
understand what makes stars glow. As you may
know, all matter is made up of particles called
atoms, and those atoms are in turn made up of
electrons, protons, and neutrons. Now, when
matter is heated, that makes the atoms jostle
around; in turns, that makes the electrons
vibrate. But since the electrons have electric
charge, when they vibrate, they give off
electromagnetic waves; the faster the electrons
vibrate, the higher the frequency of the
electromagnetic waves they emit. For example, the
electrons in your body are always giving off
infrared radiation - that's how we can see people
(and other warm things) with infrared cameras,
even when it's pitch black!
Now, as you make something hotter, the
electrons vibrate faster and faster, and the
frequency of the radiation they give off goes up.
You may have heard of or seen heated metal
glowing "red hot"; that's when its temperature
gets high enough that it starts giving off visible
light. Red light is the lowest frequency visible
light, so that's the first color something starts
to glow when it's heated. But as you heat it more
and more, it starts to glow white, then blue, as
the frequency of radiation it emits increases.
So, that should answer your question: the
hotter something is, the greater the frequency of
radiation it emits. But since blue light is
higher frequency than red light, that means that
things that glow red are cooler than things that
glow blue. So: red stars are cooler!
Hope these help!
Blue stars are hotter. This is the same
principle as objects you're more familiar with.
When you heat up a piece of metal hot enough, it
starts glowing red. As it gets hotter, it becomes
more orange, yellow, and then white (like a
lightbulb, which is so hot it emits white light).
This is the same case with stars.
Great question! Scientists often use the color
of a star to determine its temperature. They can
classify the type of star by its color (and
temperature). A red star, for instance, is about
3,500 – 6,000 F (2,000 – 3,500 C) whereas a blue
star is about 20,000 – 50,000 F (11,000 – 28,000
C)! In fact, blue stars are classified as some of
the hottest (and usually largest) objects in
All objects and I mean ALL in the universe at
a temperature above absolute zero or 0 kelvin (0
Kelvin degrees) emit thermal radiation that can be
perceived as heat. This is called thermal
radiation and we can associate the temperature of
a body with the dominant wavelength of thermal
radiation it emits. The hotter the body the
SHORTER the wavelength. So, the SUN at 5800 Kelvin
degrees emits in the visible portion of the EM
spectrum and looks greenish yellow. Humans at 300
Kelvin degrees emit in the infrared.
Then a blue star is HOTTER than a RED star. The
temperature of a blue star is 40000 Kelvin
degrees, the temperature of a red star is 3500
Red stars are cooler. They are red because they
emit red light, which is lower in energy than blue
light. Energy in turn, is proportional to
temperature, which means that higher energy
corresponds to higher temperatures.
Red stars are much cooler than blue stars. Blue
stars are the hottest, then white, then yellow,
then red, then brown. Our sun is classified in the
I personally think that blue stars are cooler,
-just kidding I know that isn't your actual
Well, to answer this, a shorter wavelength
means greater energy. This is important because if
you look at the spectrum, blue photons have more
eery than red photons so the blue star generates
more energy and more heat than the red. To answer
simply, the red stars are lower in temperature
than the blue stars. Thank you for the question!
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