hi
I i am freshman in a university and i chose astronomy as my science elective and i have a problem even though the professor explained it is still don’t understand the concept of elipces and how planets travel in them i also am facing problems with the cojunctions and oppositions the diagram is kind of confusing please i need help with this .
You might have to clarify exactly where the problems are. These questions are a little open-ended. But here’s a very brief summary:
Each planet travels around the Sun in a regular, repeated trajectory called an orbit. The shape of that orbit is an ellipse — although for most of the planets, if you looked at their orbits drawn to scale on paper, you’d be hard pressed to tell them from circles.
An ellipse has two special points called foci (plural of “focus”). The more eccentric the ellipse, the more it deviates from being circular, and the further away the foci are from each other. The Sun always sits at one focus of a planet’s orbit, and not (perhaps surprisingly) at its center. The speed at which a planet moves in its orbit also varies: it moves faster when its near perihelion (the closest orbital point to the Sun), and slower when its near aphelion (the furthest point from the Sun).
All the planets’ orbits are approximately in the same geometric plane, and they travel in the same direction. So they somewhat resemble runners running around a circular race track, each runner in a separate lane. The speeds and distances are very different though, unlike the situation on a real race track. Earth goes around its orbit once per year of course, whereas Mercury goes around once every 3 months, and it’s orbit is only about half the size of Earth’s. Meanwhile Jupiter goes around once every 12 years, and its orbit is about 5 times the size of Earth’s. Inner planets always have shorter years than outer ones.
Opposition usually refers to the moment when an outer planet, say Jupiter, is on the opposite side of the sky from the Sun as seen from Earth. This happens when the Earth “laps” the planet as the two of them race around in their orbits. At that time, the Earth will be (approximately) directly between the Sun and the planet.
Conjunction usually refers to the moment when a planet is between the Earth and Sun, or when the Sun is between the Earth and the planet. (The first case only happens for Venus and Mercury.) When a planet is at or near conjunction, it’s normally very difficult to see in the sky, since it appears close to the Sun.
Hope this helps.
Did anyone else open this thread expecting a grammar question?
Yes, and then I found one hell of a run-on sentence.
After reading his OP, I’d flunk him in every course just on general principles. :rolleyes:
Gosh you’re strict.
And the school year has only just started.
If the astronomy course doesn’t work out, there still may be time to transfer to the course “Capitalization of Personal Pronouns”.