The Plasma State Plasma is known as the fourth state of matter. The other three states are solid, liquid and gas. In most cases, matter on Earth has electrons that orbit around the atom’s nucleus. The negatively charged electrons are attracted to the positively charged nucleus. Remember, opposites attract! So the electrons stay in orbit around the ...

Read More »## Gas

Gas Gas is one of the four common states of matter. The three others are liquid, solid, and plasma. There are also some other exotic states of matter that have been discovered in recent years. The air in Earth’s atmosphere is mostly a mixture of different types of gases. A ga-s usually has much lower density than a ...

Read More »## Liquids

Liquids Liquids is one of the four common states of matter. The three others are gas, solid, and plasma. There are also some other exotic states of matter that have been discovered in recent years. A liquid does not have a fixed shape, like a solid; instead it takes on the shape of the ...

Read More »## What is a Fluid?

What is a Fluid? What is a Fluid? A fluid is anything that would spill or float away if it weren’t in a container (unless it’s big enough to be held together by gravity like a star). If you can stir it up with a spoon or blow it through ...

Read More »## Orbit Shapes Interactive Animation

Orbit Shapes Interactive Animation This interactive animation shows two important features of orbits – shape and size. Orbits are ellipses. An ellipse can be like a circle, or it can be long and skinny. Mathematicians and astronomers use the term “eccentricity” to describe the shape of an orbit. An orbit shaped ...

Read More »## Perihelion and Aphelion

Perihelion and Aphelion The closest point to the Sun in a planet’s orbit is called perihelion. The furthest point is called aphelion. Notice how the planet moves fastest at perihelion and slowest at aphelion. Randy Russell). Perihelion and Aphelion The planets in our Solar System orbit the Sun. The orbits of some planets ...

Read More »## Eccentricity of an Orbit

Eccentricity of an Orbit Eccentricity of an Orbit You may think that most objects in space that orbit something else move in circles, but that isn’t the case. Although some objects follow circular orbits, most orbits are shaped more like “stretched out” circles or ovals. Mathematicians and astronomers call this ...

Read More »## Elliptical Orbits

Elliptical Orbits Elliptical Orbits You may think that most objects in space that orbit something else move in circles, but that isn’t the case. Although some objects follow circular orbits, most orbits are shaped more like “stretched out” circles or ovals. Mathematicians and astronomers call this oval shape an ellipse. ...

Read More »## Kepler’s 3rd Law: P2 = a3

Kepler’s 3rd Law: P2 = a3 Kepler’s 3rd Law: P2 = a3 Kepler’s 3rd law is a mathematical formula. It means that if you know the period of a planet’s orbit (P = how long it takes the planet to go around the Sun), then you can determine that planet’s distance from the ...

Read More »## Kepler’s 2nd Law : The Speeds of Planets

Kepler’s 2nd Law: The Speeds of Planets Kepler’s second law he again discovered by trial and error. Kepler realized that the line connecting the planet and the Sun sweeps out equal area in equal time. Look at the diagram to the left. What Kepler found is that it takes the same ...

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