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
- K. Reinmuth
- Discovery site
- Heidelberg Obs.
- Discovery date
- 2 August 1949
- Pronunciation
- / t ɒ l ə ˈ m iː ə s /
- Named after
- Ptolemy , (Greco-Roman astronomer)
- Alternative designations
- 1949 PV · 1949 QD 1 , 1982 BU 9 · 1987 OE
- Minor planet category
- main-belt · ( inner ) , Flora
- Observation arc
- 67.75 yr (24,744 d)
- Aphelion
- 2.6809 AU
- Perihelion
- 1.8940 AU
- Semi major axis
- 2.2874 AU
- Orbital period sidereal
- 3.46 yr (1,264 d)
- Mean anomaly
- 294.51 °
- Mean motion
- 0° 17 5.64 / day
- Inclination
- 5.4568°
- Longitude of ascending node
- 130.67°
- Argument of perihelion
- 204.09°
- Mean diameter
- 4.641 ± 0.297 km , 5.0 km (est. at 0.24 )
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Named after
- Ptolemy
- Followed by
- 4002 Shinagawa
- Follows
- 4000 Hipparchus
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 4.641
- Orbital period
- 1263.293885739488
- Image
- Orbit of 4001 Ptolemaeus.gif
Show 18 more facts
- discoverer or inventor
- Karl Wilhelm Reinmuth
- site of astronomical discovery
- Heidelberg-Königstuhl State Observatory
- provisional designation
- 1987 OE
- time of discovery or invention
- 1949-08-02
- orbital inclination
- 5.456810545400354
- orbital eccentricity
- 0.1720243582502774
- absolute magnitude
- 13.75
- periapsis
- 1.893599827346061
- apoapsis
- 2.680447359221902
- semi-major axis of an orbit
- 2.287023593283982
- mean anomaly
- 12.49152443675644
- longitude of ascending node
- 130.6331803767233
- argument of periapsis
- 204.0199066476436
- Commons category
- 4001 Ptolemaeus
- albedo
- 0.392
- asteroid spectral type
- S-type asteroid
- time of periapsis
- 2460956.6653709873
- epoch
- November 21, 2025
Sources (2)
via Wikidata · CC0
~3 min read
Encyclopedic overview
4001 Ptolemaeus, provisional designation 1949 PV, is a Florian asteroid from the inner regions of the asteroid belt, approximately 5 kilometers (3.1 miles) in diameter. It was discovered on 2 August 1949, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in Heidelberg, Germany. In 1991, the International Astronomical Union named the S-type asteroid after Greco-Roman astronomer Ptolemy.
Orbit and classification
Excerpted from Wikipedia’s “4001 Ptolemaeus” article, available under the CC BY-SA 4.0 licence.