At one astronomical unit from the sun ( the Earth's distance ) the dust orbits are probably nearly circular.

At the peak of the Cretaceous transgression, one-third of Earth's present land area was submerged.

At the Survey, he worked mainly in geodesy and gravimetry, refining the use of pendulums to determine small local variations in the Earth's gravity.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground.

At the close of the 20th Century, all of the Earth's kaiju have been collected and confined in an area known as Monster Island, by the United Nations Science Committee, in the Ogasawara island chain.

At its height, the British Empire covered a quarter of the Earth's land area and comprised a quarter of its population.

The idea was used by Edgar Rice Burroughs, the creator of Tarzan, in the seven-novel " Pellucidar " series, beginning with At the Earth's Core ( 1914 ).

At that time it had lost the first page, but the second ( the current beginning of the Ynglinga Saga ) starts Kringla heimsins, " the Earth's circle " of the Laing translation.

At Standard Sea Level conditions ( corresponding to a temperature of 15 degrees Celsius ), the speed of sound is 340. 3 m / s ( 1225 km / h, or 761. 2 mph, or 661. 5 knots, or 1116 ft / s ) in the Earth's atmosphere.

At Earth's orbit its typical density is 6 ions / cm < SUP > 3 </ SUP > ( variable, as is the velocity ), and it contains a variable interplanetary magnetic field ( IMF ) of ( typically ) 2 – 5 nT.

At 10-15 kilometers ( 6 – 9 miles ) above the Earth's surface, the absorption of sunlight would further heat the smoke, lifting some, or all of it, into the stratosphere, to where the smoke would persist for years, with no rain to wash it out.

At 165. 25 million square kilometres ( 63. 8 million square miles ) in area, this largest division of the World Ocean – and, in turn, the hydrosphere – covers about 46 % of the Earth's water surface and about one-third of its total surface area, making it larger than all of the Earth's land area combined.

At first, oxygen would quickly combine with other elements in Earth's crust, primarily iron, as it was produced.

# At the Earth's Core ( 1914 )

The first novel was filmed as At the Earth's Core ( 1976 ), directed by Kevin Connor and starring Doug McClure as David Innes and Peter Cushing as Abner Perry.

* At the Earth's Core ( 1976 movie )

Image: AtTheEarthsCore. jpg | At the Earth's Core-1960s paperback

At, Russia is the largest country in the world, covering more than one-eighth of the Earth's inhabited land area.

At standard temperature and pressure, radon forms a monatomic gas with a density of 9. 73 kg / m < sup > 3 </ sup >, about 8 times the density of the Earth's atmosphere at sea level, 1. 217 kg / m < sup > 3 </ sup >.

At the measured distance of Vega, this corresponded to an actual radius of 80 astronomical units ( AU ), where an AU is the average radius of the Earth's orbit around the Sun.

At high latitudes ( near the Earth's poles ), they are very low, making communication difficult or impossible due to factors such as atmospheric refraction, Earth's thermal emission, line-of-sight obstructions, and signal reflections from the ground or nearby structures.

At that point in Earth's history these rocks made up the soft bottom sediments of a large, shallow ocean, which stretched across much of North America.

At the Earth's surface, earthquakes manifest themselves by vibration, shaking and sometimes displacement of the ground.

At an equinox, the Sun is at one of two opposite points on the celestial sphere where the celestial equator ( i. e. declination 0 ) and ecliptic intersect.

At the magnetic dip equator, where the geomagnetic field is horizontal, this electric field results in an enhanced eastward current flow within ± 3 degrees of the magnetic equator, known as the equatorial electrojet.

At the onset of the Neoproterozoic the supercontinent Rodinia, which had assembled during the late Mesoproterozoic, straddled the equator.

At the high end of estimates for the rotation velocity for Vega is along the equator ( for a rotation period of about 12. 5 hours ), which is 87. 6 % of the speed that would cause the star to start breaking up from centrifugal effects.

At the poles, the troposphere is thinner and the temperature only decreases to-45 ° C, while at the equator the temperature at the top of the troposphere can reach-75 ° C.

At surface level, the sinking air diverges again with some moving back to the equator and completing the vertical cycle.

At their intersections with the celestial sphere, these form the celestial equator, the celestial poles and the ecliptic, respectively.

* At the equator objects on the celestial poles stay at fixed points on the horizon.

At the equator, under flat conditions ( no obstructions such as mountains ; or at a height above any such obstructions ), the terminator line moves at approximately 1600 kilometers per hour ( 1000 miles per hour ).

At almost 7, 000 feet above sea level and almost exactly halfway between the equator and north pole, West Yellowstone experiences a subarctic climate ( Köppen climate classification Dfc ) with cold, sometimes bitterly cold winters, and brief but generally warm summers.

At the equator this delay between fixes was several hours ; at mid-latitudes the delay decreased to an hour or two.

At the equator the two celestial poles are at the horizon and motion is counterclockwise ( i. e. to the left ) around the North Star and clockwise ( i. e. to the right ) around the southern celestial pole.

At Oxford he extended the Cape observations of stars to the 7th magnitude from 25 ° S declination to the equator, and collected the results in the Radcliffe catalogue for 1890, which contains the places of 6, 424 stars.

At the equator, the effective gravitational acceleration is 9. 7805 m / s².

At geodetic latitude 48. 46791 … degrees ( e. g., Lèves, Alsace, France ), the radius R is 20000 / π ≈ 6, 366. 1977 …, namely the radius of a perfect sphere for which the meridian arc length from the equator to the North Pole is exactly 10000 km, the originally proposed definition of the meter.

At a declination of-29. 6 °, Fomalhaut is located south of the celestial equator, and hence is best viewed from the Southern Hemisphere.

( At the poles, though, the celestial equator would be parallel to the horizon.

) At all latitudes the celestial equator appears perfectly straight because the observer is only finitely far from the plane of the celestial equator but infinitely far from the celestial equator itself.

At the pole, the temperature may be above 20, 000 K, while the equator is at or below 10, 000 K. The average temperature of the star is about 15, 000 K. The high polar temperatures are generating a fast polar wind that is ejecting matter from the star, creating a polar envelope of hot gas and plasma.

At solar maximum, the Sun's magnetic field lines are the most distorted due to the magnetic field on the solar equator rotating at a slightly faster pace than at the solar poles.

At the equator, there is very little difference ( Pisces, Aries, Virgo and Libra take slightly less time than the other signs ) but as one moves from the equator, larger and larger differences emerge.