Does earth revolve around the sun
![does earth revolve around the sun does earth revolve around the sun](https://svs.gsfc.nasa.gov/vis/a030000/a030700/a030710/planets3x3_sun_colorMercury_axis_tilt_1080p.00001_print.jpg)
Newton's cannonball thought experiment demonstrating that orbits are just objects falling but traveling sideways fast enough to never strike the source of the gravity. Astronauts in orbit are constantly falling towards the earth and missing it.
#Does earth revolve around the sun free#
More correctly, the astronauts are in a state of free fall. They are surrounded by the earth's and the sun's immense gravity. Astronauts on the International Space Station are not in a no-gravity environment. All gravitational orbits are actually cases of falling and missing. Scientists use fancy phrases for this effect such as "stable orbit" or "closed trajectory", but fundamentally what they mean is "falling and missing". Because of this sideways momentum, the earth is continually falling towards the sun and missing it. So why don't we hit the sun and burn up? Fortunately for us, the earth has a lot of sideways momentum. The earth is literally falling towards the sun under its immense gravity. This statement is not a metaphor or a play on words. The earth and everything on it is constantly falling towards the sun because of the sun's immense gravity. Gravity is caused by mass, so objects with more mass, such as planets and stars, exert a lot of gravity. Gravity is a centrally attractive force, meaning that objects in a gravitational field always fall towards the source of the gravity. It's a good thing too, because that is what keeps the earth from flying out of the solar system under its own momentum. In fact, the earth is constantly falling down. For those of us who live in the Northern Hemisphere where it's summer in July and winter in January, that seems backwards, doesn't it? That just goes to prove that Earth's distance from the sun is not the cause of the seasons.The earth does fall down.
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While that is a difference of over 3 million miles, relative to the entire distance, it isn't much.Īnd, believe it or not, aphelion-when Earth is farthest from the sun-occurs in July, and perihelion-when we are closest-occurs in January. More about Earth's slightly elongated orbitĮarth's perihelion (point closest to sun) = 91,400,000 miles from sunĮarth's aphelion (point farthest from sun) = 94,500,000 miles from sun So if you go to South Africa for the winter holidays, bring your swimsuit and leave your skis at home. If you live in the Southern Hemisphere, the sun will be more northerly in the sky during the winter (that is, June, July, and August). During the summer, the sun tracks more directly overhead, rising in the east, overhead at noon, and setting in the west. It follows that if you live in North America, during the winter the sun's path across the sky is more toward the south, rising in the southeast and setting in the southwest. It is winter in December in the Northern Hemisphere, because that is when it is the South Pole's turn to be tilted toward the sun. It is summer in June in the Northern Hemisphere because the sun's rays hit that part of Earth more directly than at any other point in Earth's orbit - or, in other words, more directly than at any other time of the year. Thus, sometimes it is the North Pole tilting toward the sun (like in June) and sometimes it is the South Pole tilting toward the sun (like in December). So different parts of Earth get the sun's direct rays as we travel through the year. So, here we are, orbiting the sun, but tilted a bit and always with the axis pointed in the same direction. At least that is generally accepted theory. Incidentally, that big something that hit Earth also knocked a chunk of it out that became our Moon. So instead of rotating with its axis perpendicular to its orbital plane, it is tilted 23.45 degrees from the perpendicular. There is a completely different reason for Earth's seasons.Įarth has seasons because sometime early in its long history, something very big hit the young Earth to knock it off-kilter. However, in the Northern Hemisphere, we are having winter when Earth is closest to the sun and summer when it is farthest away! It is slightly elongated, so that during part of the year, Earth is closer to the sun than at other times. It is true that Earth's orbit is not a perfect circle. Although this idea makes sense, it is incorrect.