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Apsidal precession (perihelion precession) and Milankovitch cycles

Apsidal Precession (Perihelion Precession). Created by Sal Khan.

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• Talking about rotation, does anybody know if the earth's rotation is speeding up or slowing down? And it so what causes that?
• The Earth's orbit is slowing down due to the gravitational force of the moon acting on our planet
• to all who watched all the videos on precession, how many things are rotating.
• The planet around the poles, the planet around the sun, where the north pole points, where the perihelion occurs, and the eccentricity could be considered the absolute value of a sine function, so 5
• what is the difference btween an equinox and a solistice?
• an equinox is when a night and day is the same length of time. a solstice is the longest day and the longest night but may or may not be of different length.
: )
• Am I right to say that precession is a change in direction of the magnetic poles (north and south)?
• Technically, precession is the change in position of something.

What you are referring to is a geomagnetic reversal:
http://en.wikipedia.org/wiki/Geomagnetic_reversal

Precession is just the axis moving about the vertical line that is perpendicular to the Earth's orbital plane.
• This is sort of unrelated, but whenever I see depictions of our Solar System, the planets are all lined up in the same direction relative to the Sun. ( you know, like this: (earth) (mars) (jupiter) ) Is that really the case? Is it even possible for planets to be on different lines relative to the center of their orbit?
Like this: - - - -(mars) - - - - - - - - -(jupiter)

(earth)
See? Different lines relative to the Sun. Was that a helpful example?
• In answer to your first question, you might want to look up the word "syzygy". Really. It's a fun word which means an alignment of three or more celestial objects. And, yes, it happens fairly frequently for two planets and the Sun. For three or more planets in syzygy with the Sun, the occurrence happens less and less frequently as the number of planets gets larger, but it still does happen.
https://en.wikipedia.org/wiki/Syzygy_(astronomy)

For your second question, as I understand it, let's start with the Earth's orbit around the Sun. The plane which is defined from that orbit is called the "plane of the ecliptic", because that is the plane in which eclipses happen. All the planets orbit the Sun in different planes, although they are all near to the plane of the ecliptic. Their planes are inclined to the ecliptic, so the measure of their inclination is called that planet's "inclination".
https://en.wikipedia.org/wiki/Orbital_inclination

BTW, your illustration of Earth being below the plane of Mars and Jupiter was excellent, I understood exactly what you were getting at. Good job.
• Is this why we have leap years then?
• No, we have leap years because the orbit of the earth is not exactly 365 days it is about 365.242 days.
• Why do all these cycles happen?
• Because nothing we can see moves in perfect circles
• At Mr. Khan says that if our calendar was based on the perihelion, then our year would be 25 minutes longer each year, but if we're just orbiting the sun and the eccentricity isn't changing enough to affect us, than why would our years be getting longer?