| Discovery | |
|---|---|
| Discovered by | O. Struve |
| Discovery site | Williams Bay |
| Discovery date | 24 October 1922 |
| Designations | |
| (991) McDonalda | |
| 1922 NB, 1949 PF, 1950 WG, 1953 GT1, 1975 EE6 | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 80.10 yr (29255 days) |
| Aphelion | 3.6381 AU (544.25 Gm) |
| Perihelion | 2.6458 AU (395.81 Gm) |
| 3.1419 AU (470.02 Gm) | |
| Eccentricity | 0.15791 |
| 5.57 yr (2034.2 d) | |
| 351.48° | |
| 0° 10m 37.092s / day | |
| Inclination | 2.0696° |
| 63.255° | |
| 254.682° | |
| Physical characteristics | |
| 15.705±1.05 km | |
| 0.0638±0.009 | |
| C | |
| 11.12 | |
991 McDonalda is a Themistian asteroid. It was discovered by Otto Struve in 1922 at the Yerkes Observatory in Williams Bay, Wisconsin, United States. It is named after the McDonald Observatory, which Struve helped found in 1939.[2]
References
[edit]- ^ "991 McDonalda (1922 NB)". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 2 May 2016.
- ^ Lutz D. Schmadel (2011). Dictionary of Minor Planet Names. Addendum to Fifth Edition: 2006–2008. Springer. ISBN 978-3-642-01966-1.
External links
[edit]- 991 McDonalda at AstDyS-2, Asteroids—Dynamic Site
- 991 McDonalda at the JPL Small-Body Database
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction