The length of the semi-major axis multiplied by the eccentricity.
The Sun does NOT lie at the centre of an ellipse. The Sun is at one of the two foci of an ellipse. Have you ever drawn an ellipse with two pins a piece of string and pencil on a board. Insert the two pins into the board/paper. Loosely loop the string over the pins, and tighten with the edge of a pencil. Keeping the string taught with the pencil you can draw an ellipse. The positions of the two pins are the foci of the ellipse. Astronomically, the Sun lies at one of these pins. This was discovered by the Astronomer , Johannes Kepler, who gave us the law, that the Earth sweeps equal arcs in equal times about the Sun . The other focus may be thought of as a 'blind' focus. Have a look in Wikipedia under 'Johannes Kepler'. NB The plural of the noun 'focus' is 'foci'. 'Focuses' is when the word 'focus' is being used as a verb.
The imaginary elliptical path of the Earth around the Sun is called its orbit. It is not a perfect circle, but an ellipse, with the Sun located at one of the foci of the ellipse. The Earth's orbit is slightly elliptical, which means that the distance between the Earth and the Sun varies throughout the year.
Ellipse. One of Newton's Laws of Planetary Motion sate that the planets revolve in elliptical orbits with the Sun at one of the two foci.
The orbit is elliptical, and in simple cases, the centre of the two bodies' mass is at one of the foci of the ellipse.
As the eccentricity reaches zero the two foci merge together and the ellipse becomes a circle. If a is half the major axis of the ellipse, and e is the eccentricity, the distance between the foci is 2ae. For a planet the Sun occupies one focus and the other is vacant, so the Sun is a distance of ae from the centre of the ellipse. The minor axis is sqrt(1-e^2) times the minor axis, so for all the planets except Mercury the minor axis is more than 99½% of the major axis. The best way to draw an orbit is to ignore this small difference and draw a circle, and then place the Sun at the right distance off-centre.
An ellipse has 2 foci. They are inside the ellipse, but they can't be said to be at the centre, as an ellipse doesn't have one.
Most orbits are elliptical; all NATURAL orbits are. There are two foci, or focuses, to an ellipse. The distance between the foci determines how eccentric, or non-circular, they are. If the two foci are in the same place, then the ellipse becomes a circle. So a circular orbit would have only one focus.
The major axis of an ellipse is its longest diameter, a line that runs through the center and both foci, its ends being at the widest points of the shape.The semi-major axis is one half of the major axis, and thus runs from the centre, through a focus, and to the edge of the ellipse. It represents a "long radius" of the ellipse, and is the "average" distance of an orbiting planet or moon from its parent body.
The shape of the orbit of each planet is an ellipse. An ellipse is a geometric shape that is like a flattened circle. The Sun is located at one of the foci of the ellipse, not at the center.
The planets orbit in an ellipse. An ellipse is described as a geometric shape where the sum of the distance from the foci at any point is the same. An ellipse has three main points. Two foci and a center like a circle. While a true circle has all its external points equidistant from its center, an ellipse measures its points from the foci, which are equidistant to the center point at on both sides. The planets ellipse is closer to a circle than an all out ellipse, however, the orbit is still a true ellipse. It is also true that the shape of a planet's orbit (an ellipse) is a conic section, i.e. the intersection of a right circular cone where the intersecting plane is not perpendicular to the cone's axis, but less than being parallel to one of the cone's nappes.
Planets don't have circular orbits; all orbits are ellipses. A circle has one center, but an ellipse has two focuses, or "foci". The further apart the foci, the greater the eccentricity, which is a measure of how far off circular the ellipse is. Venus has the lowest eccentricity, at 0.007. Neptune is next with an eccentricity of 0.011. (Earth's orbit has an eccentricity of 0.017.) So, Venus has the shortest focus-to-focus distance.
It is a SPECIAL form of ellipse. In an ellipse the centre and the two foci are at separate points on one axid. In a circle the centre and the two foci are ALL at the circle centre.
The Earth's orbit around the sun is best described as an ellipse. An ellipse is a geometric shape that is elongated and slightly flattened. The sun is located at one of the foci of the ellipse, not at the center.
An ellipse is very eccentric when its foci are far apart.The closer one focus is to the other, the less eccentric the ellipse is.When when both foci are the same point, the eccentricity is zero, and the ellipse is a circle.
The orbit of a planet is not a circle with the sun at the center. It's an ellipse with the sun at one focus. An ellipse is an 'egg shape', or 'oval', or 'squashed circle'. It has two foci (focuses) and neither one is in the center. So you can easily see that as the planet moves along the ellipse, its distance from the sun changes, and there is a minimum distance (perihelion) and a maximum distance (aphelion). Those don't change unless the shape of the ellipse changes, and the only way that happens is through the gravitational influence of the other planets, which is relatively tiny over the course of many millennia.
Vertices and the foci lie on the line x =2 Major axis is parellel to the y-axis b > a Center of the ellipse is the midpoint (h,k) of the vertices (2,2) Equation of the ellipse is (x - (2) )^2 / a^2 + (y - (2) )^2 / b^2 Equation of the ellipse is (x-2)^2 / a^2 + (y-2)^2 / b^2 The distance between the center and one of the vertices is b The distance between(2,2) and (2,4) is 2, so b = 2 The distance between the center and one of the foci is c The distance between(2,2) and (2,1) is 1, so c = 1 Now that we know b and c, we can find a^2 c^2=b^2-a^2 (1)^2=(2)^2-a^2 a^2 = 3 The equation of the ellipse is Equation of the ellipse is (x-2)^2 / 3 + (y-2)^2 / 4 =1
The distance from the center of a lens to one of its focal points is the focal length of the lens.