If a planet is found to rotate slower than expected, then astronomers suspect that the planet is accompanied by a satellite, because the total angular momentum is shared between the planet and its satellite in order to be conserved.

: If a planet crosses ( or transits ) in front of its parent star's disk, then the observed brightness of the star drops by a small amount.

If the heavier body is much more massive than the smaller, as for a satellite or small moon orbiting a planet or for the Earth orbiting the Sun, it is accurate and convenient to describe the motion in a coordinate system that is centered on the heavier body, and we say that the lighter body is in orbit around the heavier.

If a planet is sufficiently massive, the water on it may be solid even at high temperatures, because of the high pressure caused by gravity, as it was observed on exoplanets Gliese 436 b and GJ 1214 b.

If ranked today, the United Arab Republic would be the 25th largest nation on the planet ( Egypt is 30th and Syria is 88th ).

If an instantaneous centripetal force ( red arrow ) is considered on the planet during its orbit, the area of the triangles defined by the path of the planet will be the same.

If such a planet actually existed, according to present scientific cosmology, it would be permanently hidden behind the sun but nevertheless detectable from Earth, because of its gravitational influence upon the other planets of the Solar System.

If the orbit is almost edge-on, then the planet can be seen transiting its star.

If not quite a daughter of the soil, she was a granddaughter of it, and her concern for our planet led her to become an environmentalist, indeed the first female environmentalist to achieve such resounding political success.

' If we can get this done, this is going to be the fucking coolest game that the planet Earth has ever fucking seen in its entire history!

Translating this analogy into space, then, a " stationary " observer sees a planet moving left at speed U and a spaceship moving right at speed v. If the spaceship has the proper trajectory, it will pass close to the planet, moving at speed U + v relative to the planet's surface because the planet is moving in the opposite direction at speed U. When the spaceship leaves orbit, it is still moving at U + v relative to the planet's surface but in the opposite direction ( to the left ).

If the spacecraft's purpose is only to fly by the inner planet, then there is typically no need to slow the spacecraft.

If the planet Epsilon Eridani b exists then this belt is unlikely to have had a source outside the orbit of the planet, so the dust may have been created by fragmentation and cratering of larger bodies such as asteroids.

If the eccentricity was actually this high, the planet would pass through the asteroid belt and clear it out within about ten thousand years.

If a large amount of energy is transmitted, it could heat the surface of the planet to an uninhabitable temperature.

Al Gore has argued " If you're a young person looking at the future of this planet and looking at what is being done right now, and not done, I believe we have reached the stage where it is time for civil disobedience to prevent the construction of new coal plants that do not have carbon capture and sequestration.

If the resistance at both wheels is equal, the planet gear revolves without spinning about its own axis, and both wheels turn at the same rate.

If such is the case, the particles within a distance of about Af of the Earth will have, relative to the Earth, a kinetic energy less than their potential energy and they will be captured into orbits about the Earth.

If a rotating frame is chosen so that just the angular position of an object is held fixed, more complicated motion, such as elliptical and open orbits, appears because the centripetal and centrifugal forces will not balance.

If they formed in their current locations, their orbits must originally have been circular ; otherwise accretion ( the coalescence of smaller bodies into larger ones ) would not have been possible because the large relative velocities between planetesimals would have been too disruptive.

If the initial firing is above the surface of the Earth as shown, there will also be elliptical orbits at slower velocities ; these will come closest to the Earth at the point half an orbit beyond, and directly opposite, the firing point.

If a secondary body orbits a primary body, the forces that could tear the second body apart if its strength and internal gravity are not enough, are the tidal force and the " centrifugal force " associated with any rotation of the secondary body about its axis.

* If is a polynomial, then is the boundary of the filled Julia set ; that is, those points whose orbits under iterations of remain bounded.

Note that non-elliptic orbits also exist ; If the eccentricity is greater than one, the orbit is a hyperbola.

If a spacecraft gets close to the Schwarzschild radius of a black hole ( the ultimate gravity well ), space becomes so curved that slingshot orbits require more energy to escape than the energy that could be added by the black hole's motion.

If 0 < e < 1, then the denominator of the equation of free orbits varies with the true anomaly θ, but remains positive, never becoming zero.

If the action is a locally free action or free action, then the orbits of define a foliation of.

If a conjugate of HS in Co < sub > 0 </ sub > fixes a particular point of type 3, this point is found in 276 triangles of type 2-2-3, which this copy of HS permutes in orbits of 176 and 100.

If this refers to the moon's angular width, we can infer that the moon orbits Alofmethbin at a distance of approximately 300, 000 km.

If the mass of the smaller body ( e. g. Earth ) is m, and it orbits a heavier body ( e. g. Sun ) of mass M with a semi-major axis a and an eccentricity of e, then the radius r of the Hill sphere for the smaller body ( e. g. Earth ) is, approximately

If a planet orbits its sun too closely or too far away, the surface temperature is incompatible with water being liquid ( though sub-surface water, as suggested for Europa, Enceladus, and Ceres, may be possible at varying locations ).

If the plane of reference is the equator, these orbits are called equatorial ; if the plane of reference is the ecliptic, they are called ecliptic.

If planets with masses of around an Earth mass or greater form while the gas is still present, the planets are thought to transfer angular momentum to the surrounding gas in the protoplanetary disk so that their orbits spiral gradually inwards towards the primary.

If the planet orbits in the same plane as the circumstellar disk, the inclination would be about 46 °, implying a planetary mass of 1. 5 times Jupiter.

If this happens, one says that " invariants do not separate the orbits ", and the algebra A reflects the topological quotient space X / G rather imperfectly.

If a unipotent group acts on an affine variety, all its orbits are closed, and if it acts linearly on a finite dimensional vector space then it has a non-zero fixed vector.

The theorem is then: If a flow preserves volume and has only bounded orbits, then for each open set there exist orbits that intersect the set infinitely often.

If you take the one, you'd better take both ''.

`` If you can conveniently let me have twenty dollars '', he wrote one friend in 1791 when he was Secretary of the Treasury.

If one dancer slaps another, the victim may do a pirouette, sit down, or offer his assailant a fork and spoon.

If a child had a single drop of Negro blood, he would revert to the ancestral line which, except as slaves under a superior race, had not made one step of progress in 3,000 years.

If we examine the three types of change from the point of view of their internal structure we find an additional profound difference between the third and the first two, one that accounts for the notable difference between the responses they evoke.

If in any one calculation Ptolemy had had to invoke 83 epicycles all at once, while Copernicus never required more than one third this number, then ( in the sense obvious to Margenau ) Ptolemaic astronomy would be simpler than Copernican.

If within one year you can make a success out of the American, you can practically name your own salary thereafter.

If it is not one of his best books, it can only be considered unsatisfactory when compared with his own Garibaldi.

If one finger is raised against the authorities, all our moral power will vanish.

If any one of them has any power to veto the Secretary General's decisions the nature of the organization will have changed.

If he can bounce back with one of those 25 home runs years, the club will have to be better off offensively.

If they do meet and recognize one another, slap backs and embrace, the moment soon is done.

If either one ever started making promises, there is no telling where the promises would end.

If one follows the reports of the Congress, one finds that there still seems considerable uncertainty in the minds of the leaders themselves about what exactly to do in this matter.

Somebody, got to be somebody If I don't put my two cents in soon, somebody else will I know they're waitin only for one thing: for the bastards what done it to be nailed.

If we had, then one of us would have had to go instead.

`` If I catch you one more time down here without stockings '' --

If, for some reason such as economy, we are not going to develop aircraft nuclear propulsion with a sense of national urgency, then we should turn our effort to developing jet engines with a thrust-to-weight ratio of 12 or 15 to one.

If you don't own a planer and don't want to buy one, it's well worth renting.

Note: If 1/2-inch panel board is used inside and out, or 5/8-inch one side and 3/8-inch the other, and 1/8-inch glass is used, stock lumber in Af, Af, and Af can be used in making the glass panels.

If you have a full-time doctor now, can he be replaced with a part-time doctor or one who serves on a fee-per-case basis only??

If you use one of the new year-round cooling system fluids such as `` Dowguard '' be sure to check it.

If you run into excess plug fouling on one truck, check to be sure that the rig has a thermostat.