The Earth From Space

Spacecraft views Earth's outer gas shell

This is the first ever picture taken from space of the Earth's extended helium atmosphere

June 2, 2000 - BBC

The first pictures from Nasa's Imager for Magnetopause to Aurora Global Exploration (Image) spacecraft are showing for the first time the global ebb and flow of hot, electrified gas (plasma) around the Earth as it is wafted by the solar wind.

Image was launched to study and monitor the weather in the Earth's upper atmosphere, the sheath that interacts with the particles and magnetic fields that come from the Sun.

Disturbances in this region of electrically charged gas can disrupt satellites, telephone and radio communications, and power systems.

"Image is the first weather satellite for space storms," said Dr. James L. Burch, Principal Investigator for Image at the Southwest Research Institute, San Antonio, Texas.

"This revolutionary spacecraft makes these invisible storms visible. In a sense, Image allows us to view the Earth through plasma-coloured glasses. We eagerly anticipate the arrival of severe solar weather associated with solar maximum, which we are now entering."

A cloud of energetic particles surrounding the Earth

Three so-called Neutral Atom Imaging instruments are recording the glow of fast atoms coming from throughout the Earth's magnetic field. This reveals the shape and motion of the clouds of plasma that make up a magnetic storm.

The Far Ultraviolet Imaging instrument is collecting the first-ever images from space of the Earth's proton aurora. The aurora, commonly known as the northern and southern lights, is a ghostly light show seen most often at high latitudes of Earth. The proton aurora is invisible to the naked eye and has never been viewed from space.

The Extreme Ultraviolet Imager instrument on Image is capturing the first global images of the plasmasphere, a tenuous extension of the Earth's electrically charged upper atmosphere, or ionosphere. The plasmasphere extends about 20,000 km (12,500 miles) into space. Scientists say that images from this region will provide a sensitive indicator of the onset of magnetic storm activity.

The Radio Plasma Imager instrument provides a three-dimensional view of the plasmasphere by sounding it with radio pulses, like an ultrasound image of the human body. To accomplish this, it uses the longest antenna ever deployed in space, longer than the height of the Empire State Building.

Previous spacecraft have explored this turbulent region by detecting particles and fields as they passed through them. This technique limited their vision to small portions of this vast and dynamic region that extends beyond the Moon on the Earth's night side.

"The old way of tracking magnetic storms is like trying to understand severe thunderstorms in the Midwest by driving around with a rain gauge out the window," said Dr. Thomas Moore, Image Project Scientist at Nasa's Goddard Space Flight Centre in Maryland.

"With Image, we will see the big picture, just like entire storm systems appear on the evening news with weather satellites."

First Images

"These first images are an enticing glimpse at the spectacular results expected from Image once we encounter really heavy weather in space," said Dr. James Green, Deputy Project Scientist for Image at Goddard.