What is Magnetic Field ?

Farther away, where the magnetic field is weak, they fan out, becoming less dense. A uniform magnetic field is represented by equally spaced parallel straight lines.

This information also helps us to figure out how Mercury was formed. According to two popular theories, Mercury used to be bigger but either lost its outer layers when they were fried by the Sun or when they were torn off by a large impact shortly after the planet was formed. Given the new information on volatile compounds, neither of those theories seems likely now.

Black Beauty, an ancient Mars meteorite found in 2011 in the Sahara Desert, may tell an intriguing tale of Mars’s climate history. The shiny, dark meteorite has embedded zircons, durable minerals that are created when lava cools and can survive almost all chemical attacks

The direction of the flux is the direction in which the north-seeking pole of a small magnet points.

That means they can help us to determine the age of rocks and give clues to a planet’s climate. “When you find a zircon, it’s like finding a watch,” Florida State Professor Munir Humayun said. “A zircon begins keeping track of time from the moment it’

The lines of flux are continuous, forming closed loops. For a bar magnet, they emerge from the north-seeking pole, fan out and around, enter the magnet at the south-seeking pole, and continue through the magnet to the north pole, where they again emerge.

Humayun and his team were surprised to find that some zircons in Black Beauty were created 4.4 billion years ago, when Mars was a new planet with an environment that may have had the ability to support life.

Humayun was able to extract some of Mars’s climate history like an archaeologist would extract bits of human history from artifacts and human skeletons. That’s because the zircons act like an archive of Mars’s climate change by keeping records of what happened to water vapor during the history of the planet.

The SI unit for magnetic flux is the weber. The number of webers is a measure of the total number of field lines that cross a given area.

Humayun discovered that water was much more plentiful on Mars about 4.5 billion years ago, but then a dramatic change took place. The dry desert that characterizes Mars today has existed for a long time—at least 1.7 billion years.

Magnetic fields may be represented mathematically by quantities called vectors that have direction as well as magnitude.

In the daytime, dust in the air may block sunlight from heating the surface of Mars. At night, that same type of dust emits long-wave radiation that warms the surface. So a greater knowledge of atmospheric dust—and dust devils—should help us to develop a better understanding of Mars’s current climate.

Earth is surrounded by two Van Allen radiation belts, an inner and an outer one, each shaped like a doughnut and containing high-energy electrons and protons. But in early 2014, scientists announced that NASA’s twin Van Allen Probes had discovered a strange but persistent zebra stripe pattern in the high-energy electrons in the inner radiation belt.

Two different vectors are in use to represent a magnetic field: one called magnetic flux density, or magnetic induction, is symbolized by B; the other, called the magnetic field strength, or magnetic field intensity, is symbolized by H

Earth’s magnetic field holds these radiation belts in place. But Earth seemed like an unlikely culprit in the zebra stripe mystery. Most scientists assumed that increased solar wind would cause this kind of structure. But that theory was discarded when the stripes continued to be visible even though solar wind activity was low.

The magnetic field H might be thought of as the magnetic field produced by the flow of current in wires and the magnetic field B as the total magnetic field including also the contribution made by the magnetic properties of the materials in the field.

Scientists eventually found the answer they’d previously considered so unlikely. It turns out that Earth’s rotation causes the zebra stripes. Due to the tilt in our planet’s magnetic field axis, Earth’s rotation produces a weak, oscillating electric field that affects the entire inner radiation belt. If you think of groups of electrons in the radiation belt as taffy, then the oscillations work like a candy machine to stretch and fold the taffy, which produces the striped pattern in the inner radiation belt.

The Sun has rainstorms with high winds that are surprisingly similar in some ways to the storms we experience here on Earth. But on the Sun, the rain is composed of plasma, ionized gas that falls from the corona to the surface at 200,000 kilometers (125,000 mi) per hour. The corona surrounds the Sun like an outer atmosphere. But when it rains from the corona, it truly pours. Each droplet is as large as Ireland, and there are thousands of droplets in a coronal rain shower.

When a current flows in a wire wrapped on a soft-iron cylinder, the magnetizing field H is quite weak, but the actual average magnetic field (B) within the iron may be thousands of times stronger because B is greatly enhanced by the alignment of the iron’s myriad tiny natural atomic magnets in the direction of the field.

Scientists have known about this plasma rain for about 40 years. But until they received detailed data from modern satellites and observatories, they couldn’t explain why it happened.

This is where the parallels to Earth-based weather become striking. Under the right conditions, the Sun’s clouds of dense, hot plasma will cool, condensing until they fall to the surface as coronal raindrops.

There’s also a process of rapid evaporation that forms clouds. But on the Sun, the powerful explosions of solar flares cause the evaporation. Telescopic images show that solar flares, radiation bursts on the surface of the Sun, precede solar rainstorms. Scientists believe that an unusually fast drop in temperature then causes coronal gas to morph into solar raindrops.

In addition to measuring spikes of methane, NASA’s rover Curiosity discovered organic molecules in samples from the insides of rocks. The powder from a rock called Cumberland is the first definite discovery of organics on the surface of Mars. Scientists don’t know if these organics developed on Mars or were transported there by carbon-rich meteorites.

NASA scientists didn’t find organics in material exposed on the surface of the planet. But that’s understandable because cosmic radiation and the ever-present perchlorates, which produce molecule-changing chlorine, tend to destroy surface organics over time.

Organic molecules consist of carbon linked to other elements like hydrogen. They’re essential to life as we know it, but they don’t necessarily contain life. We don’t know if Mars ever hosted living microbes, but this tells us that ancient Mars had conditions that were hospitable to certain forms of life.