- A star is a luminous spheroid of plasma held together by self-gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light. The most prominent stars have been categorised into constellations and asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated 1022 to 1024 stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy.
- Kepler (wikiquote.org)
Kepler is a short history of events leading to the astronomical discoveries of Johannes Kepler. It was written by Walter William Bryant, a staff member of the Royal Observatory, Greenwich. The book was published in 1920 by the Society for Promoting Christian Knowledge, London, and by The MacMillan Company, New York, within a series of books called “Pioneers of Progress.”