Learning about star temperatures sheds light on why they appear red or blue. Understanding black-body radiation helps explain the differences in how stars emit energy across the electromagnetic spectrum.
Black body radiation
Black body radiation refers to the energy emitted by a body across all wavelengths. The spectral energy distribution (SED) of a star shows this energy at each wavelength. Blue stars emit more energy at shorter wavelengths, while red stars emit less at those wavelengths.
This concept shows how blacksmiths know if metal is hot enough to shape. The metal glows red and gets brighter as it heats up.
Stars and the Earth’s Surface
Our view of a star is influenced by the earth’s surface. When a star’s light hits the atmosphere and scatters, it causes changes in color and twinkling. This process, known as scintillation, creates the effect.
The earth’s atmosphere is filled with moving gases, making it dense. As light passes through, it causes stars to appear to change color, especially the sun.
The sun’s color changes with its position in the sky. During sunrise and sunset, the sun appears different because it’s lower and passes through more of Earth’s atmosphere. This extra distance diffuses the light more.
Is the sun the hottest star?
The sun is a hot star, but not the hottest. Its surface temperature ranges 4,000 – 6,000°K (6,700 – 11,000 °F). The hottest known star, WR 102, has a surface temperature of 210,000 °K (377,540 °F). Despite being much hotter, WR 102 doesn’t affect Earth.
WR 102 doesn’t affect us because it’s 9,500 light-years away, or about 55.8 quadrillion miles. Although it’s the hottest star, its distance and half the size of the sun make it harmless.
| Topic | Details |
|---|---|
| Sun’s Temperature | 4,000 – 6,000°K (6,700 – 11,000 °F) |
| Hottest Star | WR 102 |
| WR 102 Temperature | 210,000 °K (377,540 °F) |
| WR 102 Distance | 9,500 light-years |
| Distance in Miles | 55.8 quadrillion miles |
| WR 102 Size | Half the size of the Sun |
| Impact on Earth | None |