NASA’s Earth Observatory provides an in-depth look at more than 2,280 satellites that are working 24/7, tracking the weather, redirecting voice and data communications, and sending GPS information to and from anywhere on the globe.
- Low Earth Orbit (LEO) the ISS, Hubble, earth observation satellites
- Medium Earth Orbit (MEO) GPS satellites
- Geosynchronous Orbit (satellite and the earth have same orbital speed)
- High Earth Orbit (HEO) weather satellites
A satellite’s “place in space” is determined by three things: its distance from the surface of the earth (the farther away, the slower the orbit), the eccentricity of its orbit (either circular or elliptical) and its inclination (whether it orbits parallel to the equator or at an angle).
For instance, a weather satellite might be positioned in a geosynchronous circular orbit to constantly monitor cloud cover, precipitation, and storm systems in a particular region, while communication satellites that cover regions over the north and south poles would follow a highly elliptical orbit inclined at a 90-degree angle.
The Roman god Mercury was a lightning-quick thief, a prankster and a traveler known for his prosperity and for his role in guiding souls down into the underworld. Centuries ago, when ancient astronomers were beginning to explore the solar system, they observed a bright, silver-colored planet that swiftly traveled across the night sky, and they named it after this mythological character.
The element mercury, also known as “quicksilver,” shares the name as well. Mercury is bright and reflective and is the only metal that stays liquid at room temperature. In the past, it was used in dental fillings and medications, but mercury is highly toxic to humans and is being replaced by environmentally-friendly products and technologies.
For instance, mercury was used in household thermometers because the shiny metal would readily expand upward inside a calibrated tube in response to changes in temperature. Digital thermometers in use today typically contain a coil of metal wire that registers a change in temperature in response to the flow of an electric current.
Its hurricane season, and a dangerous one, with as many as three or four storm systems that could potentially reach hurricane strength in the warm waters of the Atlantic Ocean. Hurricane Harvey made landfall in South Texas as a Category 4 on August 30-31. Hurricane Irma is a category 5 storm that was spinning across Puerto Rico and Cuba before making its way up the Florida coast. And the National Hurricane Watch Center at NOAA is keeping their “eye” on Hurricanes Katia and Jose as well.
Storm systems are formed when warm air rises and clashes with cold air, resulting in precipitation and heavy winds. Hurricanes and Tornadoes are made of the same elements of air and water as regular thunderstorms, but they have the potential to quickly grow in size and build up a rotational velocity that causes catastrophic destruction.
Hurricanes and Tornadoes spin simply because the earth is spinning. Meteorologists explain that a phenomenon called the Coriolis Effect causes wind and precipitation to arc toward the right in the northern hemisphere, creating storms that rotate in a counter-clockwise direction, and toward the left in the southern hemisphere, resulting in storms that spin clockwise.
Tornado alley” in the mid-western United States sees more tornado activity than any other country in the world. Cold air from the Rocky Mountains collides with warm air from the Gulf of Mexico, and winds begin to spin unpredictably. Wind direction within a tornado spins chaotically both in a circular direction and vertically. High in the sky, they’re usually connected to a dangerous cumulonimbus cloud while they touch down on earth, sweeping up anything in a pathway of destruction that could measure up to two miles wide and many miles long. Tornado alerts sound in regions where storm activity is likely, but a tornado isn’t classified until after it dissipates, allowing scientists to observe the damage it caused and place it on a scale ranging from F0-F5.
Hurricanes, in contrast, form in the ocean during the summer and early autumn. They gather speed as warm water evaporates and rises, clashing with cold air higher up in the atmosphere. As the water cools, condensation begins to form, creating torrential rainfall that contributes to coastal flooding as powerful storm surges flow inland. Hurricane winds mostly blow horizontally, and for this reason “hurricane hunters” have been known to safely fly a plane through the center of the storm, dropping instruments into the winds to measure speed and precipitation.
Extremes on Planet Earth
Hottest and Coldest: In 1922, a weather station in El Azizia, Libya recorded the temperature on September 13, 1922 to be 136 F (57 C), while the coldest place on earth was -128 C (90 C) logged by Russian scientists at a research lab in Antarctica on July 20, 1983
Highest and Lowest: Mt. Everest is known as the tallest mountain above sea level. It’s 29,029 ft (8,848 m) summit is rising approximately 2 inches per year. The deepest point below sea level is 39,070 ft (10,994 m) within the Mariana trench
Largest earthquake in the U.S: On March 28, 1964, a magnitude 9.2 jolted Prince William Sound, Alaska. …in the world: A 9.5 quake shook Chile on May 22, 1960 followed by powerful tsunamis that killed thousands
Deadliest hurricane in the U.S: Though we might guess Katrina in 2005, that was a category 3 storm compared to a category 4, the Great Galveston Hurricane, which struck Texas in September of 1900. …in the world: In November 1970, a category 3 typhoon leveled the western coast of both India and Pakistan, killing 300-500,000
When meteorites from space are found on earth, scientists can usually determine where they came from based on information about the geology of the other terrestrial planets.
An example in recent years is the meteorite NWA7034, found in the Sahara Desert in 2011. NASA scientists not only classified it as having originated on Mars, they theorize it is more than two billion years old and contains more water than other “younger” meteorites known to have come from the red planet.
Deep Space Network
The Jet Propulsion Laboratory in California is NASA’s home base for unmanned space travel. Scientists of the JPL oversee missions such as the Opportunity and Curiosity rovers on Mars, the Juno spacecraft orbiting Jupiter, and the Cassini mission exploring Saturn.
The Jet Propulsion Labs are also where NASA’s Deep Space Network is managed. The “network” is a series of dish-shaped antennas at three strategic locations around the globe; California, Madrid, and Australia. The stations are spaced approximately 120 degrees longitude apart from each other, ensuring that as the earth rotates there is a continual connection with NASA spacecraft wherever they are in the solar system.
Using the Deep Space Network, a spacecraft orbiting millions of kilometers away can be repositioned as NASA scientists send commands to change its speed and trajectory. When a spacecraft finishes the research it was tasked for, missions are often extended. Software upgrades can be transmitted to the spacecraft, sending it off in another direction within the solar system.
Spacecraft in turn “communicate” with NASA about the complex systems that keep them in flight, while transmitting detailed images from other worlds … the planets, moons, and asteroids that might otherwise never be seen from Earth.