| Webster's Online Dictionary |
| Expressions | Domain | Definition | |
| Explorer 1 | Aerospace | 1: First satellite launched by the US, around midnight of January 31, 1958. Carrying Geiger counters, Explorer 1 and the similar Explorer 3 (launched two months later) discovered the existence of a belt of magnetically trapped energetic particles around Earth. (references) | |
| 2: The first US artificial satellite, launched 31 January 1958 by a 4-stage modified military rocket. Provided the earliest observations of the Earth's radiation belt. (references) | |||
Source: compiled by the editor from various references; see credits. | Top | ||