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
- C. H. F. Peters
- Discovery site
- Litchfield Obs., Clinton
- Discovery date
- 28 June 1886
- Pronunciation
- / æ l ə ˈ θ iː ə /
- Named after
- Aletheia
- Alternative designations
- A886 MA, 1947 LD
- Minor planet category
- main-belt
- Adjectives
- Aletheian
- Observation arc
- 117.00 yr (42,736 days)
- Aphelion
- 3.5353 AU
- Perihelion
- 2.7347 AU
- Semi major axis
- 3.1350 AU
- Orbital period sidereal
- 5.55 yr (2027.5 days)
- Mean anomaly
- 71.260 °
- Inclination
- 10.813°
- Longitude of ascending node
- 86.864°
- Argument of perihelion
- 168.07°
- Earth moid
- 1.7207 AU
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Named after
- Aletheia
- Followed by
- 260 Huberta
- Follows
- 258 Tyche
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 174.318
- Mass
- 7.79
- Orbital period
- 2026.047509416458
Show 19 more facts
- discoverer or inventor
- Christian Heinrich Friedrich Peters
- site of astronomical discovery
- Litchfield Observatory
- provisional designation
- A886 MA
- time of discovery or invention
- 1886-06-28
- orbital inclination
- 10.80839047869475
- albedo
- 0.043
- Commons category
- 259 Aletheia
- rotation period
- 8.143
- asteroid spectral type
- X-type asteroid
- absolute magnitude
- 7.81
- orbital eccentricity
- 0.1299692665783229
- semi-major axis of an orbit
- 3.133531985524786
- periapsis
- 2.726269131566414
- apoapsis
- 3.540794839483159
- longitude of ascending node
- 86.78060692006358
- argument of periapsis
- 166.3287216527482
- mean anomaly
- 28.43026509114242
- time of periapsis
- 2460840.4970339444
- epoch
- November 21, 2025
Sources (2)
via Wikidata · CC0
~2 min read
Encyclopedic overview
259 Aletheia is a very large main-belt asteroid that was discovered by German–American astronomer Christian Peters on June 28, 1886, at Litchfield Observatory, Clinton, New York. The dark and heterogeneously composed X-type (Tholen: CP-type) asteroid contains primitive carbonaceous materials, responsible for its low albedo of 0.04. Aletheia measures about 185 kilometers in diameter and belongs to the largest asteroids of the main-belt. It has a semi-major axis of 3.1 AU and an orbit inclined by 11 degrees with a period of 5.55 years.
Richard P. Binzel and Schelte Bus further added to the knowledge about this asteroid in a lightwave survey published in 2003. This project was known as Small Main-belt Asteroid Spectroscopic Survey, Phase II or SMASSII, which built on a previous survey of the main-belt asteroids. The visible-wavelength (0.435-0.925 micrometre) spectra data was gathered between August 1993 and March 1999.
Excerpted from Wikipedia’s “259 Aletheia” article, available under the CC BY-SA 4.0 licence.