|MadSci Network: Astronomy|
Erik, The near-Earth asteroid known as "433 Eros" appears to have a daytime temperature of about 100 degrees C (212 deg. F) and a nighttime temperature about -150 deg. C (-238 deg. F). The NEAR (Near Earth Asteroid Rendevous) mission will visit this asteroid to make better measurements. The dust in out Solar System in the vicinity of the Asteroid Belt show temperatures as warm as -75 deg. C (-100 deg. F). This temperature was measured by the Infrared Astronomical Satellite (IRAS). The average temperature in space has been measured to be about -270 deg. C (-454 deg. F). The observed colors of the most common types of asteroids are usually very dark. This means that they will be warmer than the space around them because they will absorb the light that reaches them. We need to send spacecraft (the NEAR mission for example) to chosen asteroids and to the asteriod belt to measure the temperatures. Until we do this we know only that the temperatures will be warmer than -270 deg. C and colder than about 100 deg. C. The actual temperature depends on how much light (energy) is being absorbed by the asteroid. As we move further from the sun the asteroids will be colder. John Haberman, Space Scientist NASA/Goddard Space Flight Center
Try the links in the MadSci Library for more information on Astronomy.