Natural Environment Blog

I recently wrote about the Crew Earth Observations experiment, where crew of the International Space Station photograph the Earth.

Although photographing Earth only takes up a small portion of their time - between 10 to 15 minutes per day - these photos are a crucial part of analyzing our ever changing planet.

So, every day there are astronauts up there in the sky taking photos of us here on Earth. But before you get all paranoid, did you know that the International Space Station can actually be seen from Earth?

The International Space Station can be seen from Earth with the naked eye. It orbits the Earth at an average speed of 27,700 km (17,210 statute miles) per hour, completing 15.77 orbits per day. And, because it orbits at approximately 350 kilometers above the Earth, it is close enough to see as it zooms past your region.

To find out when the International Space Station is next traveling past your town, check out the Heavens Above website.

NASA astronauts have shared their top ten photographs of Earth as taken from space.

The photos have been taken as part of the Crew Earth Observations (CEO) experiment. The CEO experiment is an ongoing mission to provide people on Earth with data about our ever changing planet.

Astronauts have been taking photos of Earth since the early 1960s. Nowadays, the CEO experiment continues on the International Space Station (ISS), which hovers around 220 miles (354 kilometers) above Earth.

The photos to the right are included in the top ten Earth observations. The top photo was taken when Mt Cleveland erupted for about two hours in 2006.

The second photo shows what the Himalayas look like from the International Space Station. This photo includes Mount Everest (the world’s highest mountain) and Mount Makalu (world’s fifth highest mountain).

The astronauts on the International Space Station spend between 10 and 20 minutes per day taking photos of Earth. They use hand held cameras, which include 35 and 70 mm cameras.

Areas to be photographed are both pre-determined, and decided by the crew. The pre-determined areas are generally regions of Earth that have undergone change or are indicators of global change.

Many of the pre-determined sites include major deltas in south and east Asia; coral reefs; smog-prone urban regions; areas experiencing major floods or droughts triggered by El Niño cycles; high altitude glaciers, which reflect longer-term climate changes; faults associated with major tectonic plate boundaries; and unusual features on Earth, like impact craters comparable to structures on other planet.

As mentioned in my article about NASA’s Earth Observing System, NASA doesn’t only study space. NASA spends a great deal of time and money studying Earth - from outer space.

Because of its Earth Observing System (EOS), NASA is able to provide us with detailed imagery of earth, taken from space craft and satellites in outer space.

But not only do we get photos of Earth, we also get to see things like:

• tropical cyclones, typhoons, hurricanes, and other weather systems
• city lights
• fires
• the effects of deforestation
• glacier recession - an (arguable) example of the effects of global warming

NASA makes these images available at its Visible Earth website, where you can download photos for print and web. NASA makes these images freely available to anyone, as long as they adhere to the terms of use.

The Earth radiation budget represents the balance between incoming energy from the sun and outgoing (reflected) energy from the Earth.

The term ‘budget’ can be likened to an individual’s budget or company budget - income versus expenses.

The earth radiation budget is determined by calculating all of the incoming sunlight minus all of the reflected sunlight and emitted heat.

If the radiation budget is in balance, Earth’s temperature will remain constant. If the budget is out of balance, the earth will either heat up or cool down.

Currently, the global radiation budget is in balance. This means that the amount of energy coming in is the same that is leaving. Having said this, different parts of Earth are completely out of balance. But as a whole, the earth’s radiation budget is in balance.

Many things can (and do) happen to sunlight on its way to Earth. It can be reflected back into space before or even after it reaches Earth. It can also be absorbed into many of the Earth’s surfaces.

There are 3 ways that the Earth radiation budget can tip out of balance:

• the amount of incoming solar radiation changes
• the amount of greenhouse gases in the Earth’s atmosphere changes
• the amount of Earth’s reflective features changes (clouds, ice, aerosols etc). Bright white surfaces reflect more sunlight than they absorb. The opposite is true for darker objects.

Since 1978, NASA scientists have been studying the earth’s radiation budget closely. When they launched the Nimbus-7 satellite, it carried a new instrument they called the Earth Radiation Budget Experiment (ERBE). ERBE was designed to measure all the energy through the top of the Earth’s atmosphere.

Since then, NASA has launched many more projects and satellites in order to study this area.

Blue Marble - The Photo

Blue Marble is the name given to the most famous photograph taken of planet Earth.

The photo was taken on 7 December, 1972, by the crew of the Apollo 17 spacecraft. The photo was taken from a distance of about 45,000 kilometers from Earth.

Here’s Blue Marble - the photo:

Blue Marble - The Photo Series

Blue Marble is also the name that NASA has given to a series of Earth photos. As technology has advanced, NASA has been able to take more detailed imagery of Earth from space. In 2002, NASA produced the (then) most detailed, true-color image of Earth ever. It was able to do this by stitching together imagery from the Terra satellite.

Then in 2005, NASA was able to produce an image with twice the detail. This version is called Blue Marble: Next Generation and uses imagery taken from the Terra and Aqua satellites. To obtain the data, these satellites use a NASA sensor called the Moderate Resolution Imaging Spectroradiometer (MODIS).

Blue Marble - Free to Download!

All Blue Marble images are available free of charge to educators, scientists, museums, businesses, and the public.

The collection includes images that are sized for different media, including Web and print. Users can download images of the entire globe, or just selected regions of interest.

You can download Blue Marble from NASA’s Visible Earth website.

The European Space Agency (ESA) in Paris has just released computer generated images of space junk floating around Earth. The images are intended to provide a realistic picture of the space junk that is actually floating around in space.

More than 12,000 pieces of space junk is orbiting around Earth. At least 11,500 of those are in low Earth orbit, which means they’re at an altitude of between 800 and 1,500 km. This is where most commercial, military, scientific and navigational satellites operate.

Space junk that orbits at this altitude will eventually burn up in the Earth’s atmosphere, but this could take decades. It’s rare that space junk crashes to Earth but it can (and does) happen. Most of the time space junk lands in the ocean or in isolated stretches of land.

The following image depicts the 11,500 pieces of space junk in low Earth orbit:

The following image depicts this junk from the North Pole:

As well as the space junk orbiting in low Earth orbit, there’s at least 1,147 pieces in geostationary orbit. This is where it orbits in the direction of the Earth’s rotation, at an altitude of approximately 35,786km. This altitude is where telecommunication satellites usually operate.

The following image depicts the 1,147 pieces of space junk orbiting in geostationary orbit:

With more than 600 satellites in orbit, the amount of space junk is increasing by at least 200 per year.

Space junk is usually created through collisions, explosions and lost or discarded material from space flights and rockets.

Earth Day is an annual observance aimed at raising an awareness of and an appreciation of Earth’s natural environment.

Actually, there are two different observances called Earth Day. Each have the same aim, but they are held on different days. The two different Earth Days are:

• The United Nations’ International Earth Day (or the “Equinox” Earth Day)- This is held each year on the March equinox (around March 20), and was founded in 1969 by John McConnell.
• The April 22 Earth Day - held each year on April 22nd in many countries around the world. Founded by Gaylord Nelson as an environmental teach-in. This version of Earth Day has been held annually around the world since 1970.

There are a number of different websites dedicated to the different Earth Days. For example, the US has an Earth Day website providing info about Earth Day and how to live in a more sustainable way. Here’s what it says about Earth Day:

Earth Day is a time to celebrate gains we have made and create new visions to accelerate environmental progress. Earth Day is a time to unite around new actions. Earth Day and every day is a time to act to protect our planet.

There is also the International Earth Day website, which includes the Earth Charter, as well as a plea from John McConnell, the Earth Day founder for there to be a singular Earth Day.

Whichever Earth Day you celebrate, it’s a good opportunity to think of the progress we’ve made so far, as well as consider the new ways we can help protect our environment.

Most people, when they think of NASA, think of space exploration. And fair enough too. That’s primarily what NASA was set up to do - to study space. And after all, NASA does stand for National Aeronautics and Space Administration.

But what many people don’t know, is that NASA also studies earth - from space. Ever since its creation in 1958, NASA has been studying the earth to some degree.

NASA’s Earth Science Program

In 1991, NASA got more serious about its earth studies and launched a program specifically to address this area. The program, which is called Earth Science Enterprise (ESE), includes the Earth Observing System (EOS) - a system for studying the earth comprehensively.

The purpose of ESE is:

To develop a scientific understanding of Earth’s system and its response to natural or human-induced changes, and to improve prediction of climate, weather, and natural hazards.

The program consists of three main components:

• A series of satellites - These can be used to obtain high resolution imagery photos of the earth.
• An advanced data system - With the ability to support the satellite system.
• And teams of scientists - These teams study the data captured by the satellites and stored in the data system.

The key areas that the program studies include:

• clouds
• water and energy cycles
• oceans
• chemistry of the atmosphere
• land surface
• water and ecosystem processes
• glaciers and polar ice sheets
• the solid Earth

ESE aims to “expand our perspective of the global environment and climate”. In doing so, they hope to find out whether and how Earth can sustain the pressures we’re now placing on it.

For more info, see NASA’s Earth Science page.