NASA/Johns Hopkins University Applied Physics Laboratory

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The NEAR (Near Earth Asteroid Rendezvous) mission sought to answer fundamental questions about the nature and origin of the many asteroids and comets close to Earth's orbit. These near Earth objects may contain clues about the formation of Earth, other planets in the Solar System, and may even reveal information about the formation of the Universe. Eros's pristine surface offers a look at the conditions in the Solar System when the Earth formed more than 4.5 billion years ago.

The Rotation Sequence

This animation was compiled on February 12, 2000 from 780 images acquired by the MSI (Multi-Spectral Imager) camera on board the NEAR spacecraft. The images were taken every 26 seconds to create this sequence which covers over one rotation. By examining the changing shadows as Eros rotates, scientists can interpret the origin of the features on its surface.

Ellen Cohen

NASA

Earth is the only planet among the inner planets that has a significant magnetic field. The domain of the magnetic field is called the magnetosphere. The magnetosphere extends about 10 Earth radii in the direction of the Sun where a shock front called the magnetopause is formed by the interacting solar wind (charged particles that stream out from the Sun). In the opposite direction of the Sun, the magnetotail points away from the Sun for over 1000 Earth radii.

Northern and Southern Lights

We see evidence of our magnetic field when charged particles penetrate the magnetosphere and enter the upper atmosphere. When this occurs, the sky glows in colorful curtains of light, a phenomena called the Aurora Borealis (Northern Lights) and Aurora Australis (Southern Lights). Most aurorae occur at an altitude between 80 and 160 kilometers (50-100 miles). The light is created when electrons excite and ionize atmospheric gases, principally oxygen and nitrogen. Because the electrons are confined to the magnetic field lines, and these lines enter the Earth at the Magnetic North and South Poles (which are offset slightly from the geographic North and South Poles), the auroral displays typically take place at higher latitudes.

About the visualization: seeing a magnetic storm

In March 2000, the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) was launched. IMAGE uses neutral atom, ultraviolet, and radio imaging to explore three primary scientific objectives, (1) to identify the dominant mechanisms for injecting plasma into the magnetosphere on magnetic storm time scales, (2) to determine the response of the magnetosphere to changes in the solar wind, and (3) to discover how and where magnetospheric plasmas are energized, transported, and lost during magnetic storms. This animation is composed of neutral atom images of a storm cloud (incoming solar particles) in the Earth's magnetosphere. We are looking from the Sun toward Earth. The red colors represent the highest intensity of incoming particles while the blue and violet represent the lowest intensity.

Ellen Cohen

Mordecai-Mark Mac Low (American Museum of Natural History) and Kevin Zahnle (NASA Ames Research Center)

Motivated by the Comet P/Shoemaker-Levy 9 impact with Jupiter in the summer of 1994, scientists began to calculate the effects of such an impact on the comet as well as the planet. Comet Shoemaker-Levy 9 entered the Jovian atmosphere at 60 kilometers/second (about 40 miles/second) causing the comet to transform into a plasma. The temperature of the comet rose to about 50,000 K (90,000° F). As the comet entered the atmosphere, turbulence from the shock wave stripped away any loose fragments sending them streaming back into the wake. As the temperature and pressure increased, the comet was crushed, flattened, and spread out into a trail of debris before being completely destroyed.

Simulation details

Using a complex computer code to calculate the structure and density of the gas, scientists were able to predict what would happen to the gas in the Jovian atmosphere during the collision. Because a comet is such a loose body, the calculations were performed assuming a fluid body for the impacting comet. As the comet enters the atmosphere, a shock wave forms in front of the comet. Traveling deeper and deeper, turbulence begins to take its toll, breaking up the comet. Eventually, it explodes sending material high up into the atmosphere. As this material falls back into the atmosphere, it produces the spots or scars that were seen on Jupiter for months after the collision.

About the visualization: seeing a magnetic storm

In March 2000, the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) was launched. IMAGE uses neutral atom, ultraviolet, and radio imaging to explore three primary scientific objectives, (1) to identify the dominant mechanisms for injecting plasma into the magnetosphere on magnetic storm time scales, (2) to determine the response of the magnetosphere to changes in the solar wind, and (3) to discover how and where magnetospheric plasmas are energized, transported, and lost during magnetic storms. This animation is composed of neutral atom images of a storm cloud (incoming solar particles) in the Earth's magnetosphere. We are looking from the Sun toward Earth. The red colors represent the highest intensity of incoming particles while the blue and violet represent the lowest intensity.

Brian Abbott