All natural orbits are ellipses. We can force an artificial satellite into a spherical orbit, but it won't STAY there without occasional adjustments.
The "primary body" - in this case, the Sun - is at one of the two focuses (foci) of the orbit. If the focus is very close to the "center" of the ellipse, then the eccentricity of the orbit (how much it varies from a perfect circle) is close to zero.
The planets follow Kepler's law of planetary motion which says they travel in ellipses. A circle is a special case of an ellipse with eccentricity equal to zero. Some planets have elliptical orbits with very low eccentricity, so their orbits are almost circular.
Kepler's laws of planetary motion, which have been around for 400 years, say that a planet's path or orbit has the shape of an ellipse as a result of the Sun's inverse-square gravitational force. The shape of an ellipse is measured by its eccentricity factor, which expresses how far each focus is from the centre (the Sun is always at one focus). A circle is a special case of an ellipse with zero eccentricity. The eight planets have orbits with low eccentricity, so the best way to draw a planetary orbit is to draw a circle with a pair of compasses. Apart from Mercury, Mars has the most eccentric orbit, with eccentricity of 9%, which means that the minor axis of the ellpise is only 0.4% smaller than the major axis. The other six planets have less eccentricity and orbits which are even more nearly circular.
The planets and all other objects in the solar system move in elliptical orbits round the Sun. That's a sort of "oval", roughly. The shape of the orbits was discovered by Johannes Kepler and published in 1609. The amount of elongation of an ellipse is measured by a parameter called the eccentricity (a circle is an ellipse with zero eccentricity). In the case of the eight planets (except Mercury) the eccentricity is low and the shape of the orbit is very close to a circle but with the Sun displaced from the centre by an amount equal to the eccentricity multiplied the the average distance (the semimajor axis). Mars has the highest eccentricity of all the eight planets other than Mercury. Mars's orbit has a semimajor axis of 1.524 astronomical units and eccentricity of 0.0934. The minor axis of the ellipse is 99.6% of the major axis, so the orbit looks like a circle, but the centre of the circle is 0.142 astronomical units away from the Sun, so Mars's distance varies from 1.382 to 1.666 astronomical units. Kepler's achievement in discovering that Mars's orbit is an ellipse rather than the offset-circle used in the Ptolemy theory is highly impressive and it depended on the very accurate observations and measurements made by his employer, Tycho Brahe.
Earth's orbit is not highly elliptical; it has a modest eccentricity of 0.0167. An eccentricity of zero defines a perfectly circular orbit. Pluto's eccentricity is 0.248, and Mercury's is 0.2056. Neptune's largest moon, Triton, has as perfectly circular an orbit as can currently be measured. See link for more.
The earth's orbit is almost a circle, but not quite. It is elliptical, but the difference between the closest and farthest points is less than 4%. This is such a small difference that it would look like a circle to most people. Astronomy books often show misleadingly exagerated elliptical orbits.
According to the Hubble classification system, an E0 galaxy should appear almost perfectly circular in shape, with an E7 appearing highly elliptical. In effect, as the number gets larger the eccentricity of the ellipse increases, so an E0 has no eccentricity!
The planets follow Kepler's law of planetary motion which says they travel in ellipses. A circle is a special case of an ellipse with eccentricity equal to zero. Some planets have elliptical orbits with very low eccentricity, so their orbits are almost circular.
All orbits are elliptical. Some, like Earth's are ALMOST circles, but every orbit has at least a little bit of eccentricity.
Earth's orbit is an ellipse, but not by very much. The eccentricity of earth's orbit (the measure that relates to the degree of ellipticity) is .016710219, which you can compare to the eccentricity of Pluto at .24880766. Pluto's orbit is very elliptical at roughtly .25. A perfect circle has a eccentricity of zero. Eccentricity of orbits can be anything from zero to less than one. If Earth's orbit were highly elliptical, it would probably interfere with orbits of other planets, Mars in particular. This would first of all call into question the definition of Earth and Mars as planets. It would also change the lengths of the seasons in some unpredicatable ways (some seasons would be much longer than others), which would have some serious effects on living things and stability of temperature.
The Earth's orbital path around the Sun isn't a circle; it is an ellipse, a sort of oval shape. Some orbits are ALMOST circular, like the Earth's; some are more oval, like Pluto's. A comet has an elliptical orbit which is VERY stretched out.An ellipse doesn't have a center, exactly; it has a "focus". Actually, it has TWO "foci", which define the ovalness of the ellipse. The Sun is at one focus of the Earth's elliptical orbit. (There is no physical object at the other focus of the ellipse.)The Moon's orbit is elliptical, too, with the Earth at one focus of the ellipse.
Kepler's laws of planetary motion, which have been around for 400 years, say that a planet's path or orbit has the shape of an ellipse as a result of the Sun's inverse-square gravitational force. The shape of an ellipse is measured by its eccentricity factor, which expresses how far each focus is from the centre (the Sun is always at one focus). A circle is a special case of an ellipse with zero eccentricity. The eight planets have orbits with low eccentricity, so the best way to draw a planetary orbit is to draw a circle with a pair of compasses. Apart from Mercury, Mars has the most eccentric orbit, with eccentricity of 9%, which means that the minor axis of the ellpise is only 0.4% smaller than the major axis. The other six planets have less eccentricity and orbits which are even more nearly circular.
The Earth's orbit is elliptical and it takes a year to get round the ellipse once. The ellipse is almost a circle - the minor axis is only 0.014% smaller than the major axis. The Sun is off-centre by 2.5 million kilometres and the Earth is closest in January (147.1 million km) and furthest in July (152.1 million km), when it is at either end of the major axis of the ellipse.
The orbits of periodic comets and the orbits of planets have the same geometric shape.Every closed gravitational orbit is an ellipse. But the eccentricity of the cometary ellipsesare almost all greater than the eccentricities of the planetary ones.
The planets and all other objects in the solar system move in elliptical orbits round the Sun. That's a sort of "oval", roughly. The shape of the orbits was discovered by Johannes Kepler and published in 1609. The amount of elongation of an ellipse is measured by a parameter called the eccentricity (a circle is an ellipse with zero eccentricity). In the case of the eight planets (except Mercury) the eccentricity is low and the shape of the orbit is very close to a circle but with the Sun displaced from the centre by an amount equal to the eccentricity multiplied the the average distance (the semimajor axis). Mars has the highest eccentricity of all the eight planets other than Mercury. Mars's orbit has a semimajor axis of 1.524 astronomical units and eccentricity of 0.0934. The minor axis of the ellipse is 99.6% of the major axis, so the orbit looks like a circle, but the centre of the circle is 0.142 astronomical units away from the Sun, so Mars's distance varies from 1.382 to 1.666 astronomical units. Kepler's achievement in discovering that Mars's orbit is an ellipse rather than the offset-circle used in the Ptolemy theory is highly impressive and it depended on the very accurate observations and measurements made by his employer, Tycho Brahe.
It is a wavy ellipse. Wavy because of the Moon. The ellipse is close to a circle, but the Earth is just a little closer to the Sun in the Northern Hemisphere's Winter. All orbits are ellipses. The gravitational perturbations caused by the Moon causes VERY TINY ripples in the elliptical path; "wavy ellipse" may be overstating the case.
Earth's orbit is not highly elliptical; it has a modest eccentricity of 0.0167. An eccentricity of zero defines a perfectly circular orbit. Pluto's eccentricity is 0.248, and Mercury's is 0.2056. Neptune's largest moon, Triton, has as perfectly circular an orbit as can currently be measured. See link for more.
English Language Keyboards:* An ellipse is a geometric shape. There is not a special key for geometric shapes. However, the letter O in some fonts is almost elliptical e.g. Oo, or you may be able to insert an elliptical symbol using the drop-down 'Insert' menu in your word-processing toolbar. * If you want to insert an ellipsis, which is a mark indicating a missing word, the customary way of doing this is by using three dots ...