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
- Max Wolf
- Discovery site
- Heidelberg Observatory
- Discovery date
- 18 January 1903
- Alternative designations
- 1903 LB; 1943 FC;, 1949 FW; 1951 RB 2 ;, 1951 SE; 1955 FB
- Minor planet category
- Main belt
- Observation arc
- 113.22 yr (41352 d)
- Aphelion
- 3.6114 AU (540.26 Gm )
- Perihelion
- 2.7270 AU (407.95 Gm)
- Semi major axis
- 3.1692 AU (474.11 Gm)
- Orbital period sidereal
- 5.64 yr (2060.7 d )
- Mean anomaly
- 201.00 °
- Mean motion
- 0° 10 28.92 / day
- Inclination
- 20.854°
- Longitude of ascending node
- 357.30°
- Argument of perihelion
- 355.03°
- Dimensions
- 77.44 ± 2.3 km
- Mass
- 4.9×10 kg
- Mean density
- 2.0 g/cm
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Followed by
- 502 Sigune
- Follows
- 500 Selinur
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 74.457
- Mass
- 490
- Orbital period
- 2054.998737783967
Show 18 more facts
- discoverer or inventor
- Max Wolf
- site of astronomical discovery
- Heidelberg-Königstuhl State Observatory
- provisional designation
- A903 BK
- time of discovery or invention
- 1903-01-18
- orbital inclination
- 20.83486287400562
- Commons category
- 501 Urhixidur
- albedo
- 0.052
- rotation period
- 13.1743
- absolute magnitude
- 9.49
- orbital eccentricity
- 0.1418708178595755
- semi-major axis of an orbit
- 3.163312433763898
- periapsis
- 2.71453071164045
- apoapsis
- 3.612094155887347
- longitude of ascending node
- 357.1817720395528
- argument of periapsis
- 357.022617690217
- mean anomaly
- 74.72392571167232
- time of periapsis
- 2460573.9511860562
- epoch
- November 21, 2025
Sources (2)
via Wikidata · CC0
~1 min read
Encyclopedic overview
501 Urhixidur is a relatively large (ranked 372nd by IRAS) main belt asteroid. It was discovered on 18 January 1903, by astronomer Max Wolf (1863–1932), at the Heidelberg Observatory in southwest Germany. Like 500 Selinur and 502 Sigune, it is named after a character in Friedrich Theodor Vischer's then-bestseller satirical novel Auch Einer.
Its rotational period was reported as 15 hours in 1992, but corrected to 13.174 hours in 2013.
Excerpted from Wikipedia’s “501 Urhixidur” article, available under the CC BY-SA 4.0 licence.