1.
Semi-major and semi-minor axes
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In geometry, the major axis of an ellipse is its longest diameter, a line segment that runs through the center and both foci, with ends at the widest points of the perimeter. The semi-major axis is one half of the axis, and thus runs from the centre, through a focus. Essentially, it is the radius of an orbit at the two most distant points. For the special case of a circle, the axis is the radius. One can think of the axis as an ellipses long radius. The semi-major axis of a hyperbola is, depending on the convention, thus it is the distance from the center to either vertex of the hyperbola. A parabola can be obtained as the limit of a sequence of ellipses where one focus is fixed as the other is allowed to move arbitrarily far away in one direction. Thus a and b tend to infinity, a faster than b, the semi-minor axis is a line segment associated with most conic sections that is at right angles with the semi-major axis and has one end at the center of the conic section. It is one of the axes of symmetry for the curve, in an ellipse, the one, in a hyperbola. The semi-major axis is the value of the maximum and minimum distances r max and r min of the ellipse from a focus — that is. In astronomy these extreme points are called apsis, the semi-minor axis of an ellipse is the geometric mean of these distances, b = r max r min. The eccentricity of an ellipse is defined as e =1 − b 2 a 2 so r min = a, r max = a. Now consider the equation in polar coordinates, with one focus at the origin, the mean value of r = ℓ / and r = ℓ /, for θ = π and θ =0 is a = ℓ1 − e 2. In an ellipse, the axis is the geometric mean of the distance from the center to either focus. The semi-minor axis of an ellipse runs from the center of the ellipse to the edge of the ellipse, the semi-minor axis is half of the minor axis. The minor axis is the longest line segment perpendicular to the axis that connects two points on the ellipses edge. The semi-minor axis b is related to the axis a through the eccentricity e. A parabola can be obtained as the limit of a sequence of ellipses where one focus is fixed as the other is allowed to move arbitrarily far away in one direction

2.
238P/Read
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238P/Read is a main-belt comet discovered on 2005 October 24 by M. T. Read using the Spacewatch 36 inch telescope on Kitt Peak and it has an orbit within the asteroid belt and has displayed the coma of a traditional comet. It fits the definition of an Encke-type comet with, before it was discovered 238P came to perihelion on 2005 July 27. When it was discovered on 2005 October 24, it showed vigorous cometary activity until 2005 December 27, outgassing likely began at least 2 months before discovery. The activity of 238P is much stronger than 133P/Elst-Pizarro and 176P/LINEAR and this may indicate that the impact assumed to have triggered 238Ps activity occurred very recently. Observations of 238P when it was inactive in 2007 suggests that it has a small nucleus only about 0.6 km in diameter and it last came to perihelion on 2011 March 10, and will next come to perihelion on 2016 October 22. 238P/Read was the target of a proposal in NASAs Discovery Program in the 2010s called Proteus. Discovery programs founding mission was to an asteroid, but it went to a Near-Earth asteroid, a mission to a main-belt asteroid was proposed in the 1990s