Galileo's notes recording Neptune as a 'fixed star'
Observing notes on Jupiter's satellites, 28 December 1612 and 28 January 1613
Galileo's notes on Jupiter's moons plot a 'fixed star' near Jupiter on 28 December 1612, which Charles Kowal and Stillman Drake identified in 1980 as Neptune. On 28 January 1613 he drew it again and noted that it and a neighbouring star 'then seemed farther apart' the night before: he had seen it move. The site's ephemeris puts Neptune's retrograde station on the very day of his first sighting, when its motion was near zero; Kowal and Drake do not offer this as the reason he missed it.
- Author
- Galileo Galilei
- Date
- 28 December 1612 – 28 January 1613
- Original language
- Latin/Italian (notebook)
- Kind
- Observation record
- Planets
- Neptune
Editions
2 editions.
| Year | Edition | © |
|---|---|---|
| 1980 | C. T. Kowal and S. Drake, 'Galileo's observations of Neptune', Nature 287 (1980): 311–313 | © |
| 1981 | E. M. Standish Jr. and Kowal & Drake reply, Nature 290 (1981): 165 | © |
Read it
One digitised copy.
- C. Kowal, 'Galileo's Observations of Neptune', DIO 15 (2008) 3–6DIO, The International Journal of Scientific History©Open ↗Archived copy
Copies stay with their holders; every link opens their site. Licence: PD public domain · CC BY · CC BY-SA · © rights reserved · ? not stated.
Myths we don’t repeat
Checked, and left out.
- Myth 01
Not Kowal and Drake's explanation: the story that Galileo missed Neptune's motion because it was at a station comes from later popular retellings.
Checked against the ephemeris
Same day as the retrograde station.
| Source date | Planet | Station R | Station D | Sign | Where it falls |
|---|---|---|---|---|---|
| 28 Dec 1612 | Neptune | 28 Dec 1612 | 4 Jun 1613 | Virgo | Same day as the retrograde station |
Recomputed with the site’s ephemeris (astronomy-engine 2.1.19). All times UTC.
References
Also on the Early modern and modern shelf
| Date | Source | Planets | Kind |
|---|---|---|---|
| 1543 (manuscript c. 1520–1541) | De revolutionibus orbium coelestiumNicolaus CopernicusMath. astronomy | Me Ve Ma Ju Sa | Math. astronomy |
| c. 1580–1600 | Tycho Brahe's Mars observationsTycho BraheObservation | Ma | Observation |
| 1609 | Astronomia novaJohannes KeplerTheory / model | Ma | Theory / model |
| 1632 | Dialogo sopra i due massimi sistemi del mondoGalileo GalileiTheory / model | Me Ve Ma Ju Sa | Theory / model |
| 1647 | Christian AstrologyWilliam LillyAstrological | Me Ve Ma Ju Sa | Astrological |
| presented 7 August 1709 | Cassini's apparent path of MercuryJ. D. CassiniMath. astronomy | Me Ju Sa | Math. astronomy |