| LOCKYER | Norman ___, astronomer jointly credited with detecting the element helium (7) |
| RHENIUM | Element helium with nickel in strange surroundings (7) |
| CASSINI | Giovanni _; astronomer with a spacecraft named after him (7) |
| RAREGAS | Any of the unreactive elements helium, neon, argon, krypton, radon and xenon (4,3) |
| HE | Symbol for the element helium (2) |
| LEIBNITZ | Wilhelm ____ is jointly credited for the discovery of calculus |
| MASON | Charles ___, astronomer who, with Jeremiah Dixon, surveyed the boundary between Maryland and Pennsylvania in colonial America (5) |
| HERSCHEL | William ___, astronomer who discovered the planet Uranus in 1781 (8) |
| BRAHE | Tycho ___, astronomer who established the Uraniborg Observatory in Denmark (5) |
| APARTHEID | Help about element helium separation |
| TEST | In chemistry, what is the process of detecting the presence of an ingredient in a compound? (4) |
| RADAR | System for detecting the direction, presence of aircraft, ships by high-frequency radio waves reflected from the object |
| EUREKA | Archimedes' cry when he had thought of a method of detecting the adulteratjon of the gold for Iliero's crown (6) |
| SONAR | Apparatus for detecting the presence of submarines (5) |
| ASDIC | Apparatus for detecting the presence of submarines (5) |
| GEIGER | ___ counter, instrument for detecting the presence of radiation (6) |
| SAGAN | Carl _; astronomer and writer of Cosmos (5) |
| HALLEY | Edmond ___, Astronomer Royal from 1720-42 (6) |
| RYLE | Martin ___, Astronomer Royal from 1972-82 (4) |
| RUBIN | Vera ___, astronomer born in 1928 noted for her research on galaxy rotation rates |
