Remote Sensing & Satellite Imagery Messana Science 8
Warm Up • What is the picture to the right? • What do you see in the picture? (Land Features, weather, etc..) • How could this picture be useful? • What is the location?
Remote Sensing • Remote sensing is the process of gathering information about something without actually making contact with the object. • Satellites are the best = Satellite Imagery
What are the uses of satellite imagery? • Weather (including storm damage) • Observation & Monitoring (land use/urban sprawl/deforestation) • Scientific research (Global warming) • Communications • Navigation (GPS) • Military • Map-making
How does it work? • As energy from the sun strikes the earth (light), it interacts with the objects/materials on earth differently. • Step 1: Satellite orbits earth & records energy reflected • Step 2: This data is transmitted back to earth as computer code • Step 3: The code is turned into electronic dots (pixels) on a screen • Step 4: Many pixels combine to form an image of the area (similar to graph paper squares)
Light can either be: Transmitted means the energy passes through an object. Absorbed means energy is taken in by the object. Reflected means energy bounces off of an object. Example: When light strikes a leaf, red light is absorbed and green light is reflected. The green light enters your eye and that is what you see. Behavior of Light/ Energy
The Sun • Energy from the sun travels in Electromagnetic (EM) waves. • - transfer energy through a field • (space) without using matter. • EM waves have several types which all make up the EM spectrum.
Electromagnetic Spectrum: Light from the sun travels in different types of waves • Gamma Rays: highest energy, damage cells • X-Rays: Used for imaging • Ultraviolet: can damage skin • Visible: Includes colors of rainbow • Infrared: Heat • Microwave: microwave ovens • Radio: Lowest energy light
Electromagnetic Spectrum Satellites measure reflectance of different wavelengths in order to figure out what material the waves are hitting and create images of Earth (Spectral Analysis) Review: What determines the color you see when you look at someone’s shirt?
Remote Sensing Uses: • Allows forest or wildlife professionals to manage resources • Showpatterns of logging and forest growth. Ensures forests are not cut down too quickly (DEFORESTATION). • GPS also allows scientists to track animals and monitor their survival.
Remote Sensing Uses: • Urban Sprawl is the spreading out of city features such as neighborhoods and shopping districts. • Scientist compare images of urban areas to the same area 20- 30 years ago. • Allows city planners to predict or manage city growth. • Also helps protect natural areas before they are damaged by urban sprawl.
Urban Sprawl • In 2002, the United States lost an average of 2 acres of farmland to URBAN SPRAWL every minute. Urban sprawl caused the loss of 6 MILLION acres of farmland between 1992 and 1997.
Map-Making - Topographic Maps • Show location and elevation of natural and artificial features of a region • Created using survey techniques and SATELLITE IMAGERY • These maps show physical features using color, lines and symbols • Elevation can be shown using contour lines - the closer the lines, the steeper the elevation!
Limits to Satellite Imagery Satellites can not YET show very small images clearly (GROUND TRUTHING used) Satellites can indicate elevation changes but can not show precise elevations (GROUND TRUTHING CAN)
Pop Quiz • Complete on a separate sheet. • Define reflectance. • What is it called when you gather information about a place without physically going? • Which is of higher energy, gamma rays of microwaves? • Which is of lower energy, x- rays or visible light? • What type of rays could be thought of as heat?