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Picture of the Day · NASA
Pathfinder on Mars
2026-07-04
On July 4th, 1997, using its own array of fireworks, a parachute, and a cocoon of airbags, the Mars Pathfinder spacecraft bounced like a giant beach ball at least 15 times before it came to rest on the surface of Mars at 10:07 AM Pacific Daylight Time. After its then novel airbag-assisted landing sequence was completed, Pathfinder transmitted this color mosaic to mission operators on Earth. In the scene from another world, the Mars Sojourner robot rover is visible in the foreground, crouched on top of the unfolded Pathfinder. About the size of a large house cat, the six-wheeled, solar-powered Sojourner became the first successful Martian rover. Surrounding Pathfinder are deflated airbags and the rock-strewn terrain of the Ares Vallis floodplain. In the distance Martian hills appear against a dusty brownish sky. The Pathfinder lander was subsequently renamed the Carl Sagan Memorial Station.
via NASA APOD
Key facts
- Discovered by
- H. E. Wood
- Discovery site
- Johannesburg Observatory
- Discovery date
- 16 January 1912
- Pronunciation
- / p r ɪ ˈ t ɔːr i ə /
- Alternative designations
- 1912 NW
- Observation arc
- 92.04 yr (33619 d)
- Aphelion
- 3.9279 AU (587.61 Gm )
- Perihelion
- 2.8955 AU (433.16 Gm)
- Semi major axis
- 3.4117 AU (510.38 Gm)
- Orbital period sidereal
- 6.30 yr (2301.7 d )
- Mean anomaly
- 87.1149 °
- Mean motion
- 0° 9 23.04 / day
- Inclination
- 20.526°
- Longitude of ascending node
- 252.032°
- Argument of perihelion
- 38.637°
- Mean radius
- 85.185 ± 1.3 km , 80.49 ± 5.58 km
- Mass
- (4.58 ± 0.28) × 10 kg
- Mean density
- 2.09 ± 0.45 g/cm
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Followed by
- Q157108
- Follows
- Q157097
- Parent body
- Sun
- Diameter
- 170.37
- Orbital period
- 2290.547894545287
Show 19 more facts
- discoverer or inventor
- Harry Edwin Wood
- site of astronomical discovery
- Union Observatory
- provisional designation
- A912 BE
- time of discovery or invention
- 1912-01-16
- orbital inclination
- 20.56605193507118
- Commons category
- 790 Pretoria
- albedo
- 0.0384
- rotation period
- 10.37
- asteroid spectral type
- P-type asteroid
- absolute magnitude
- 8.04
- orbital eccentricity
- 0.1563249180996915
- semi-major axis of an orbit
- 3.400639801277617
- periapsis
- 2.869035062856343
- apoapsis
- 3.932244539698892
- longitude of ascending node
- 251.7975691539416
- argument of periapsis
- 37.51322673005868
- mean anomaly
- 261.1875866523748
- time of periapsis
- 2461629.207125968
- epoch
- November 21, 2025
Sources (2)
via Wikidata · CC0
~1 min read
Encyclopedic overview
790 Pretoria is a minor planet orbiting the Sun that was discovered by English astronomer Harry Edwin Wood on January 16, 1912. It is a member of the Cybele group located beyond the core of the main belt (see Minor planet groups) and named after Pretoria, the capital city of South Africa.
10μ radiometric data collected from Kitt Peak in 1975 gave a diameter estimate of 175 km. In the present day it is estimated to be 170 km (106 mi) in diameter. Photometric measurements of the asteroid made in 2005 at the Palmer Divide Observatory showed a light curve with a period of 10.370 ± 0.002 hours and a brightness variation of 0.08 ± 0.03 in magnitude.
Excerpted from Wikipedia’s “790 Pretoria” article, available under the CC BY-SA 4.0 licence.