| PICARD | Jean, 17th Century French astronomer who measured the size of the Earth to a reasonable degree of ac |
| JEANPICARD | 17th-century French astronomer who measured the size of the Earth to a reasonable degree of accuracy (4,6) |
| RACINE | Jean ---, 17th Century French tragic poet and dramatist whose plays included Andromaque (6) |
| LACHESIS | In Greek mythology, the Fate who measured the thread of life |
| TRACE | Ground plan of a fortification; an amount of rain too small to be measured; the sum of the diagonal elements of a square matrix; or, a line marked by a recording instrument (5) |
| ATOM | If an apple were magnified to the size of the Earth, this would be close to the size of an apple |
| ASTRONOMICALUNIT | Distance equal to the mean distance from the centre of the earth to the centre of the sun (12,4) |
| LALANDE | Surname of the French astronomer who, in his Histoire Celeste, catalogued the positions of about 50,000 stars (7) |
| MESSIER | French astronomer who compiled a catalogue of 110 astronomical objects that he observed through a sm |
| ICECAP | You'll have to go to the ends of the earth to find this top hat (3,3) |
| GEODESY | Branch of science concerned with measuring the shape and size of the Earth and its features (7) |
| CASSINI | Giovanni Domenico _, Italian-born French astronomer who discovered (1675) the gap between the two brightest rings (7) |
| POLARICECAPS | What one has to go to the ends of the Earth to find |
| UNICAST | A message sent to a single recipient, especially in a computer network (anagram of "AC units") (7) |
| MAGMA | Hot molten rock that solidifies on the surface of the earth to form igneous rock (5) |
| GEODESISTS | Experts in determining the exact shape and size of the earth |
| MIT | Sch. that measured the Harvard Bridge in "Smoots," units based on the height of a student named Oliver Smoot |
| LAPLACE | French astronomer who wrote the seminal "Celestial Mechanics" |
| ELEMENT | Fire, water or earth to a Greek, or part of an electric kettle (7) |
| SOUNDED | Made a noise when measured the depth of a hole (7) |
