Lesson Summary

Students discover that sunlight and the electromagnetic spectrum are the main tools with which we study objects in the solar system. They estimate the energy output of the Sun using a simple device and discover how much power sunlight provides to Earth. The students learn that the Sun is the main source of energy on Earth. They also estimate what the effect closer to the Sun – at the distance of Mercury – might be. Essential Question How much energy does sunlight provide to Earth and what is its role in Earth’s energy resources?

The Sun seen in extreme ultraviolet wavelengths. The surface of the Sun shows the granular structure of convective cells, while a few prominences erupt on the surface at the right-hand side of the picture. (Picture credit: NASA/SOHO; http://sohowww.nascom.nasa.gov/)

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Essential Concepts

• Radiation from the Sun is the main source of energy on Earth.
• The Sun heats the Earth to a temperature at which life is sustainable.

MESSENGER Mission Connection

Sunlight is essential for MESSENGER. Many of the instruments study the reflected light off Mercury's surface (visible light) or the infrared radiation emitted by Mercury's surface heated by sunlight. The amount of particle radiation from the Sun around Mercury is also investigated. But since Mercury is so much closer to the Sun than the Earth, Mercury receives up to 11 times the sunlight as Earth, the spacecraft and its instruments can heat up significantly. Therefore, the MESSENGER mission designers have had to come up with ways to deal with the problem of excess sunlight.