Eight Motions of the Earth
"While most of our weather involves interactions between the earth /
moon / sun / solar activity some long term weather variations may be due
to lesser known earth motions"
Fifty years of space exploration from the earth infographic
The Earth has a circumference (distance around at the Equator) of
approximately 40,075 km (24,901 mi)
The Earth rotates on its axis relative to the Sun in one "mean solar
It rotates exactly 360° in one "Mean Sidereal Day" which is
86,164.0909 seconds, or 23 hrs 56 min 4.0909 seconds
How far you travel depends on your latitude...
Distance in km
= 360 * (111.41288 * cos(latitude) - 0.09350 * cos(3 * latitude) +
0.00012 * cos(5 * latitude)) speed at the equator...
speed = distance/time = circumference/time
= 40,075 km / 23 hrs 56 min 4.0909 seconds = 1,674
km/hr (1,040 mi/hr) So you are travelling faster than the speed of sound towards the
eastern horizon but Earth's rotation is slowing down - about 1 second
every 40,000 years.
The North Star will be Vega instead of Polaris by the year 14,000 AD
Both the Moon and the Earth orbit a common centre of gravity
The mass of the Earth (M
E) is 5.9742 * 10 24
kg, and the mass of the Moon is 7.349 * 10 22 kg - the Ratio
of the masses is 81.3 So the centre of gravity is therefore
located 1 unit from the Earth's centre and 81.3 units from the Moon's
centre Earth pivots around this point once every Lunar Month
The Earth's orbit around the Sun is an ellipse and travels at
different speeds during the year - slowest at Aphelion (furthest point
from the Sun) and fastest at Perihelion (closest point to the Sun)
Earth's orbit (the path) is approximately 940,000,000 km
(580,000,000 mi) in 365.2421896698 days
So the "year" is not exactly 365¼ days (sometimes called the Julian
Earth's speed around the sun
Speed = distance/time =
circumference/time = 939,951,145 km / (365.2421896698 days * 24
hr/day) = 107,229 km/hr
The Sun's mass is 1.9891 * 10
30 kg it is 332,950 times
heavier than the Earth. The Earth does cause the Sun to
wobble but it is a very tiny motion. On the other hand, Jupiter (the heaviest planet in the solar system)
causes a much more appreciable wobble in the Sun.
Sun wobbles around a point just outside its surface every 11.859
years (the length of Jupiter's orbit).
Although slow, this wobble is detectable - and it also means the
Earth is orbiting a slowly wobbling Sun
The Earth's North-South rotation axis "wobbles" like the slow
rotational tilting of a spinning top over a period of 25,770 years.
This is known as Precession and affects the direction in the sky to
which the North Pole points and, in fact, the orientation of the
entire orbital path of the Earth.
Precession is caused by the gravitational attraction of the Sun
(and the Moon) tugging on the Earth's equatorial bulge.
The Sun's position in the Milky Way Galaxy is about 2/3 of the way
out from the center to the edge of the galactic disk, (and about 20
light years north of the galactic plane).
Estimates of the Sun's distance from the centre of the Milky Way
Galaxy range from about 25,000 to 28,000 light years (a light year is
The Milky Way Galaxy and the Andromeda Galaxy are approaching each
other at about 400 km/s
The Earth wobbles causing the location of the North and South Poles
to vary by 3 to 15 m.
This Chandler Wobble causes the latitude of any position on the
Earth to move a few metres in this 14 month cycle
and affects GPS readings