Voyager: How are scientists collecting information from satellites?

Answer: Satellites give scientists an incredible amount of information about the planet and how it is changing. For example, much of what oceanographers had only suspected about ocean dynamics such as the formation of eddies and fronts only became well understood because of the use of satellites.

Satellites allow us to look at the planet in several different ways and from different perspectives and distances. They also create a lasting record of images that we can compare with future data.   

Satellites give us more information than regular cameras because they can "see" several segments of the electromagnetic spectrum that measures the wide range of energy in the universe. The light our eyes see is the visible portion of the spectrum, but there are parts you can't see, such as the microwaves that heat your food or the cell phone transmissions you use to call your friends.

Here are a few ways that satellites "see" these non-visible parts of the earth:

• They can send a pulse of microwave energy down to specific parts of the earth — the sea surface, for example — and measure the time it takes for the pulse to return.  That information can help scientists determine sea surface height.
• Lasers on satellites can detect and calculate the concentration of different chemicals in the atmosphere.
• Satellites can measure the earth's gravitational field, helping scientists identify changes in the mass distribution of the Earth.
• By examining thermal infrared radiation emitted by the sea surface, satellites can determine the ocean's temperature.
• Satellites can measure the intensity of colors at different parts of the ocean, which helps reveal areas with large amounts of chlorophyll, sediments and dissolved organic chemicals.

Satellites help scientists monitor everything from deforestation in places like the Amazon to the effects of climate change on glaciers, from rapidly changing weather to ocean currents all over the world! They have become invaluable tools that help us understand our planet better.

-- B. Greg Mitchell, research biologist, Integrative Oceanography Division