The Universe: Orbital speed, comets and more

The basics of the universe solely consists of information you need to remember, there aren't much theory's its more of just stating facts that you need to know.

Lets start with the basics, the planets. I don't personally have an acronym or song for remembering them but if you do, comment it below for other viewers. The planets listed below are listed in order:

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune

Mercury, Venus, earth and Mars are what we call the Molten cores. Jupiter, Saturn, Uranus and Neptune, however, are solid cores or gas giants.

Comets:

Firstly, the difference between asteroids and Comets is that asteroids are solid lumps of rocks while comets are a combination of ice, gas and dust. The reason we talk about comets is due to there irregular orbits. Here you can see a highly elliptical orbit. As the comet comes closer to the sun, it accelerates due to the gravitational force pulling it towards the sun. However once it is directly next to the sun (peak speed/acceleration) after that it begins to decelerate, this is due to the gravitational pull of the sun being in the opposite direction as its trajectory.

The tail of a comets direction reflects that of the direction the sun is. To elaborate on that, i mean that if the sun is on the right of the comet, the tail will be on the left of the comet. This is due to the tail consisting of melting ice due to the solar winds given off by the sun.

Orbits

Elliptical orbit: is similar to that off a circles however is disturbed by other plants gravitational pull therefore pulling/pushing it out of a circular orbit into a elliptical orbit
Circular orbit: Moons tend to orbit planets with a circular orbit
Highly elliptical orbits: as mentioned before, comets have highly elliptical orbits.

Gravity

Anything with mass has a gravity. Gravitational strength is in direct proportion to distance, as the distance increases the gravitational strength decreases - never to 0 however. The distance (radius of orbit) from the sun to the earth is counted as 1 Astronomical unit. if we were to double the distance, we would square the force.

Gravitational field strength and orbital speed

Mass Vs Weight:

Mass is the amount of stuff in you, like density
Weight is the force of gravity being pulled down

Calculate Weight:

To calculate the weight, you do mass * gravitational field strength. This can change with the planet due to the change in mass. For example, the GF of Mercury is 3.8 therefore is my mass was 100 my weight on mercury would be 380

Remember: Gravitational field strength is dictated by its mass - not its size.

Orbital Speed:

Similar to the equation of speed = distance / time, the equation for orbital speed is :

Orbital speed = 2 x π x Orbital Radius / Orbital Period

Where:

2 x π x Orbital Radius = is to calculate the circumference / distance traveled
Orbital Period = the time it takes to travel 1 full rotation or circumference .

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