Hi Alex,

That's a good question. The answer is yes, other stars can be hotter or colder than our own Sun. The temperatures of stars change as they evolve throughout their lifetime. Scientists use the Hertzsprung-Russell (HR) diagram to group stars based upon their brightness and temperature and help them understand stellar evolution. This diagram is named after Danish astronomer Ejnar Hertzsprung (1873-1967) and American astronomer Henry Norris Russell (1877-1957). Ejnar Hertzsprung was the first person to plot stellar brightness versus surface temperature. When scientists created the HR diagram by plotting the brightness of stars against their surface temperatures, they saw several distinct groups of stars. One broad band of stars runs from the upper left corner of the HR diagram (hot, bright stars) to the lower right corner (cool, faint stars). This group of stars is called the main sequence. Many stars, including our Sun, are main sequence stars. You can learn more about the main sequence and see the HR diagram here:

http://observe.arc.nasa.g...tellardeath_1ai.html

Kris