Image by WikiImages on Pixabay · Pixabay License
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
- Johann Palisa
- Discovery date
- 8 October 1879
- Pronunciation
- / k ə ˈ l ɪ s t oʊ /
- Named after
- Callisto
- Alternative designations
- A879 TA
- Minor planet category
- Main belt
- Adjectives
- Kallistoan / k æ l ɪ ˈ s t oʊ ə n /
- Observation arc
- 136.52 yr (49863 d)
- Aphelion
- 3.13704 AU (469.295 Gm )
- Perihelion
- 2.20244 AU (329.480 Gm)
- Semi major axis
- 2.66974 AU (399.387 Gm)
- Orbital period sidereal
- 4.36 yr (1593.3 d )
- Average orbital speed
- 18.22 km/s
- Mean anomaly
- 230.567 °
- Mean motion
- 0° 13 33.398 / day
- Inclination
- 8.28673°
- Longitude of ascending node
- 205.123°
- Argument of perihelion
- 55.4125°
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Named after
- Callisto
- Followed by
- 205 Martha
- Follows
- 203 Pompeja
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 48.566
- Mass
- 120000000000000000
- Orbital period
- 1593.381535361562
Show 22 more facts
- discoverer or inventor
- Johann Palisa
- site of astronomical discovery
- Pula Observatory
- time of discovery or invention
- 1879-10-08
- asteroid spectral type
- S-type asteroid
- orbital inclination
- 8.270719477174804
- density
- 2
- apparent magnitude
- 14.19
- albedo
- 0.194
- different from
- Callisto
- Commons category
- 204 Kallisto
- provisional designation
- A879 TA
- rotation period
- 19.489
- absolute magnitude
- 8.98
- orbital eccentricity
- 0.1760365892209029
- semi-major axis of an orbit
- 2.669813361094549
- periapsis
- 2.19982852315107
- apoapsis
- 3.139798199038029
- longitude of ascending node
- 204.8976094081552
- argument of periapsis
- 56.95549025443547
- mean anomaly
- 276.4003837998474
- time of periapsis
- 2461370.5169022684
- epoch
- November 21, 2025
Sources (3)
via Wikidata · CC0
~1 min read
Encyclopedic overview
204 Kallisto is a fairly typical, although sizeable Main belt asteroid. It is classified as an S-type asteroid. Like other asteroids of its type, it is light in colour. It was discovered by Johann Palisa on 8 October 1879, in Pola, and was named after the same nymph Callisto in Greek mythology as Jupiter's moon Callisto.
Photometric measurements during 2009 produced a lightcurve that indicated a sidereal rotation period of 19.489±0.002 h with a variation amplitude of 0.18±0.02 magnitudes. This result conflicted with previous determinations of the period, so the latter were ruled out.
Excerpted from Wikipedia’s “204 Kallisto” article, available under the CC BY-SA 4.0 licence.