Definition: semimajor axis: The semimajor axis of an ellipse (e.g. a planetary orbit) is 1/2 the length of the major axis which is a segment of a line passing thru the foci of the ellipse with endpoints on the ellipse itself.
Semimajor axis
2.13 AU (320 million km, 198 million miles)
3.73 AU (560 million km, 348 million miles) ...
semimajor axis
the average distance of an orbiting body from its parent body
setting circles ...
SEMIMAJOR AXIS - Half of the longest diameter, a, of an ellipse. Together with the semi-minor axis (b) and eccentricity (e), it forms a set of related values that completely describe the shape of an ellipse: ...
Semimajor axis
one-half of the longest dimension of an ellipse.
Seyfert Galaxy
a main-sequence star which rotates rapidly, causing a loss of matter to an ever-expanding shell.
semimajor axis (a): Half of the longest axis of an ellipse.
SETI: Search for Extra-Terrestrial Intelligence.
Semimajor axis -- a property of an ellipse, equal to half its greatest width, as measured along the line connecting its two foci.
semimajor axis - (n.)
Half the major axis, that is, for an ellipse, half the longest diameter.
SETI - (n.) ...
Name Semimajor Axis (km) Period (days) Eccentricity Inclination (deg) Mean Radius (km) Mass (10^20 kg)
Naiad
48,227
0.294396 ...
semimajor axis (IMO Meteor Glossary) Abbr. a. Half the length of the major axis of an ellipse or other geometric figure; a standard element used to describe an elliptical orbit. semimajor axis (NASA SP-7, 1965) (symbol a ) ...
[ Top of Page ]
370. Semimajor Axis
Half the long diameter of an ellipse.
An ellipse with a semimajor axis a and semiminor axis b, centered at the point (h,k) and having its major axis parallel to the x-axis may be specified by the equation
frac{(x-h)^{2}}{a^{2}} + frac{(y-k)^{2}}{b^{2}} = 1 .
semimajor axis (symbol a ) One-half the longest diameter of an ellipse. semiminor axis (symbol b ) One-half the shortest diameter of an ellipse.
0 au, and perihelion distances qSee also: Asteroid, Aten asteroids, Perihelion distance, Semimajor axis Asteroid One of a number of objects ranging in size from sub-km to about 1000 km, most of which lie between the orbits of Mars and Jupiter; ...
semimajor axis One-half of the longest dimension of an ellipse. shatter cone Striated conical fracture surfaces produced by meteorite impact into fine-grained, brittle rocks such as limestone.
August 28 1789 Orbital characteristics Semimajor axis
237,948 km Eccentricity
0.0047 C. C. Porco et al. (2006). "Cassini Observes the Active South Pole of Enceladus". Science 311 (5766): 1393-1401. Orbital period
1.
Five parameters determine an orbit: a semimajor axis and e eccentricity in addition to (,i,).
The size and shape of an orbit are specified by its semimajor axis and by its eccentricity. The semimajor axis is a length equal to half the greatest diameter of the orbit.
Within the main belt are groups of asteroids that cluster with respect to certain mean orbital elements (semimajor axis, eccentricity, and inclination). Such groups are called families and are named for the lowest numbered asteroid in the family.
An asteroid with a semimajor axis of 3.3 AU, for example, makes two circuits around the Sun in the time it takes Jupiter to make one and is thus said to be in a two-to-one (written 2:1) resonance orbit with Jupiter.
Half of the major axis is termed a semimajor axis. The length of a semimajor axis is often termed the size of the ellipse.
The terrestrial planets have distances from the Sun in the AU range: the semimajor axis of Mercury is 0.39 AU, that of Venus is 0.72 AU, and that of Mars is 1.52 AU. Once we turn to the giant planets, we jump to a length scale of tens of AU.
498, semimajor axis 14065 km, which yields perigee and apogee heights of 680 and 14700 km. Bargby considered them to be fragments of a larger body which broke up in December 1955.
If a is taken to be the semimajor axis of the orbit of one body around the other, then r1 will be the semimajor axis of the first body's orbit around the center of mass or barycentre, ...
Modelling simulations by Wilner's team (including Matt Holman, Paul Ho, and Marc Kuchner) suggested that the semimajor axis of the planet's orbit may center around 30 AUs -- at Neptune's orbital distance in the Solar System.
82 yrs and a semimajor axis of 1.490 AU. Nereus may be an extinct comet. MUSES-CN is a Japanese nanorover, a small, book-sized rover designed to be sent to explore the asteroid Nereus. MUSES will be launched from Japan in Jan.
Transneptunians are asteroids (minor planets) whose orbits have a semimajor axis beyond the orbit of the orbit of Neptune (but some of them have a perihelion inside the orbit of Neptune).
An asteroid family is a population of asteroids that share similar orbital elements, such as semimajor axis, eccentricity , and orbital inclination....
).
According to the The Bright Star Catalog the orbital period of the two stars about their common center of mass is 878 years. The semimajor axis of the orbit is 2.90 sec of arc corresponding to 540 AU at the distance of the stars.
The six elements needed to determine the orbit of a Solar-System body are the semimajor axis a (in AU), the eccentricity e, the inclination i of the object's orbital plane to the ecliptic, the longitude of the ascending node, ...
If you have two satellites (#1 and #2) orbiting a planet, Kepler's third law says: (period #1/period #2)2 = (distance #1/distance #2)3, where the distance is the average distance of the satellite from the planet---the orbit's semimajor axis.
Kepler's third law
The square of the period of a planet's orbit is proportional to the cube of that planet's semimajor axis; the constant of proportionality is the same for all planets.
Thus to an Earth-based observer a star describes an ellipse on the celestial sphere with a semimajor axis of 20'.49. (The eccentricity of the ellipse is zero - i.e.
90° true anomaly always occurs.
an orbiting spacecraft crosses the planet's equatorial plane going north.
180° true anomaly always occurs.
an orbiting spacecraft crosses the semimajor axis going north.
It means that if you know the period of a planet's orbit (P = how long it takes the planet to go around the Sun), then you can determine that planet's distance from the sun (a = the semimajor axis of the planet's orbit), because P2 = a3.
4 solar masses, with a semimajor axis separation of only 2.8 solar radii.
 See also: Major axis, Orbit, Axis, Planet, Period
|
