UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
Which stars are cooler red or blue?
Answer 1:

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!

Answer 2:

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.


Answer 3:

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 space

.

Answer 4:

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 Kelvin.


Answer 5:

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.


Answer 6:

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 yellow range.


Answer 7:

I personally think that blue stars are cooler, -just kidding I know that isn't your actual question.

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!



Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2015 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use