How old is the universe? How was it created? How has it evolved over time? These are only a few questions about the origins of the universe that have baffled many scientists since the dawn of curiosity. The study of the origin and evolution of the universe is often termed cosmology (in contrast with cosmogony, which refers to the study of the origin of the solar system). Astronomers have set for themselves three major tasks in the field of cosmology: to understand how galaxies evolved from the earliest times to the present; to refine and extend the scale of cosmic distances; and to test fundamental theories of the expanding universe.

Since the dawn of curiosity, intellectuals have speculated about the origins of the universe. Such speculations have led to several different theories, such as the Big Bang Theory. Even though the Big Bang Theory has not been proven, it is considered the dominant scientific theory about Earth's origin.

Age of the Universe

Recently, the Hubble Space Telescope was used to measure the distance to a galaxy named "M100". Based on this distance (56 million light-years), the age of the universe is apparently 8 to 12 billion years. Yet there are stars right here in our own galaxy that are believed to be older than that! How can the universe be younger than stars contained in it?

Stellar evolution theory and observations of globular clusters (believed to contain the oldest stars in the galaxy) give estimates for the ages of the stars of 15-18 billion years. The distance scale measurements and big bang theory suggest the universe is 8-12 billion years old. Hence, either stellar evolution theory is incorrect, or how we measure distances is wrong.

How Big Is The Universe

The Universe is an enormous almost unfathomable size. When you look at the night sky and make a wish upon your favorite star, you may not be wishing on a star at all. What most of us perceive with our eyes to be stars are sometimes much much more. Some of the objects in the night sky are actually just the planets in our solar system reflecting the sun's bright sunlight. Other objects may be comets or a whole galaxy of stars.

The Plasma Universe

More than 99 percent of matter in the Universe exists in the plasma state though nature rarely produces plasma on Earth's surface. Earth's electrically neutral environment is a rare exception.

Plasma processes are important factors in the behavior of stars, interstellar clouds, comets, the aurora, and even in our upper atmosphere. If scientists are to fully understand astrophysical and geophysical phenomena, they first must have a clear understanding of how matter behaves in the plasma state.

Years before the space era, ground-based radio wave observations revealed that a region of plasma exists above Earth's electrically neutral atmosphere. The ionosphere effectively reflects most radio waves back to Earth, and it is this process that led to the region's discovery. Plasma begins to dominate Earth's environment in the ionosphere. Ionospheric plasma is very thin and has distinctive layers that differ in composition and density: the F1 layer (around 200 kilometers) and F2 layer (around 300 to 400 kilometers). In the F2 layer, where the plasma is most dense, there are rarely more than 1 million electron-ion pairs in a cubic centimeter (cc), or thimbleful, of space; in comparison, the neutral gas density for the same region is typically 1 billion particles per cc. (Neutral gas density at Earth's surface is approximately 10 billion billion particles per cc.) The plasma in these layers, consisting mainly of electrons and atomic oxygen ions, is sustained by the ionizing action of solar ultraviolet radiation on the neutral atmospheric gas. All ionospheric layers tend to merge at night.

With the advent of artificial scientific satellites, researchers measuring the characteristics of the space environment near Earth discovered that Earth's ionized atmosphere extends much higher than was originally thought. Minute quantities of ionized atmosphere are found in Earth's magnetopause, which stretches between the lower and denser layer of the ionosphere (known as the E-layer) and the interplanetary boundary of Earth's magnetic field. On the side of Earth facing the Sun, the magnetopause extends upward from 140 to 64,000 kilometers. The behavior of the gas in this region is controlled by Earth's geomagnetic field, and the region is, therefore, referred to as the magnetosphere. The magnetopause trails away from the Sun on the night side of Earth, forming the magnetotail, which extends well beyond the orbit of the Moon (more than 384,000 kilometers), and forms a shape similar to a comet's tail.

Plasma is strongly influenced by both magnetic and electric forces, and in turn, plasma particles affect the distribution of magnetic and electric fields. Beyond the magnetopause, energetic plasma from the Sun (the solar wind) rushes past Earth at speeds ranging from 300 to 1,000 kilometers per second. While most of this solar wind is deflected around Earth, some of it penetrates the magnetosphere. The interaction between the solar wind and the magnetospheric plasma acts like an electric generator [called the magnetospheric MagnetoHydroDynamic (MHD) generator], creating electric fields deep inside the magnetopause. These fields create a general circulation of the plasma (a current system) and accelerate some electrons and ions to higher energies.

See Pictures from space

Mir Space Station

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