Solids, liquids and gases are known as states of matter.

Liquids may be divided into two general categories: pure liquids and liquid mixtures. On Earth, water is the most abundant liquid, although much of the water with which organisms come into contact is not in pure form but is a mixture in which various substances are dissolved.

Sublimation is the process of transformation directly from the solid phase to the gaseous phase, without passing through an intermediate liquid phase. At temperatures and pressures below those of the triple point, a phase change between the solid and gas phases can take place.

Solid, Liquids, and Gases. Sold, liquid, and gas all have volume and shape. They are all made up of atoms, molecules, or ions. Liquids and solids can be referred to as condensed phased because their particles are close together. Liquids and gases flow easily because their particles can move or slide past one another.

At a certain temperature, the particles in a liquid have enough energy to become a gas. The process of a liquid becoming a gas is called boiling (or vapourization), while the process of a gas becoming a liquid is called condensation.

A plasma has some unique qualities that causes scientists to label it a “fourth phase” of matter. A plasma is a fluid, like a liquid or gas, but because of the charged particles present in a plasma, it responds to and generates electro-magnetic forces.

A gas contains uncharged atoms, while a plasma contains ions and free electrons, both of which are charged particles.

The Sun is our nearest star. It is, as all stars are, a hot ball of gas made up mostly of Hydrogen. The Sun is so hot that most of the gas is actually plasma, the fourth state of matter. The first state is a solid and it is the coldest state of matter.

It does not have easily identifiable boundaries like rocky planets like Earth. Instead, the sun is composed of layers made up almost entirely of hydrogen and helium. These gases carry out different functions in each layer, and the sun’s layers are measured by their percentage of the sun’s total radius.

The inner layers are the Core, Radiative Zone and Convection Zone. The outer layers are the Photosphere, the Chromosphere, the Transition Region and the Corona. IRIS will focus its investigation on the Chromosphere and Transition Region.

Color and Temperature

Our Sun is white, and it would look white if you looked at it from space. The atmosphere scatters sunlight, especially light of shorter wavelength, i.e. blue light.

On the final three orbits, Parker Solar Probe flies to within 3.8 million miles of the Sun’s surface — more than seven times closer than the current record-holder for a close solar pass, the Helios 2 spacecraft, which came within 27 million miles in 1976, and about a tenth as close as Mercury, which is, on average.

You can get surprisingly close. The sun is about 93 million miles away from Earth, and if we think of that distance as a football field, a person starting at one end zone could get about 95 yards before burning up.

The fastest man-made object is a manhole cover that was blasted into space by an underground nuclear test.

NASA’s Parker Solar Probe is the first-ever mission to “touch” the Sun. The spacecraft, about the size of a small car, travels directly through the Sun’s atmosphere –ultimately to a distance of bout 4 million miles from the surface.