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
- J. Palisa
- Discovery site
- Vienna
- Discovery date
- 21 March 1923
- Pronunciation
- / h ɪ ˈ l ær ɪ t æ s /
- Alternative designations
- 1923 NM
- Observation arc
- 88.16 yr (32200 days)
- Aphelion
- 3.5220 AU (526.88 Gm )
- Perihelion
- 2.6535 AU (396.96 Gm)
- Semi major axis
- 3.0878 AU (461.93 Gm)
- Orbital period sidereal
- 5.43 yr (1981.8 d )
- Mean anomaly
- 93.831 °
- Mean motion
- 0° 10 53.94 / day
- Inclination
- 0.65948°
- Longitude of ascending node
- 347.404°
- Argument of perihelion
- 147.140°
- Mean radius
- 14.765 ± 0.65 km
- Synodic rotation period
- 10.05 h (0.419 d )
- Geometric albedo
- 0.0901 ± 0.009
via Wikipedia infobox
Wikidata facts
- Diameter
- 29.128
- Orbital period
- 1986.485404969243
Show 14 more facts
- provisional designation
- A923 FC
- time of discovery or invention
- 1923-03-21
- orbital inclination
- 0.6575620915186634
- albedo
- 0.12
- rotation period
- 10.05
- absolute magnitude
- 11.17
- orbital eccentricity
- 0.1387769235790386
- semi-major axis of an orbit
- 3.092606287236214
- periapsis
- 2.66342390085238
- apoapsis
- 3.521788673620048
- longitude of ascending node
- 347.1259142064537
- argument of periapsis
- 145.6515768222222
- mean anomaly
- 352.7702457438638
- time of periapsis
- 2461040.3938925313
Sources (2)
via Wikidata · CC0
~1 min read
Article
996 Hilaritas is a Themistian asteroid. It was discovered in 1923 by Austrian astronomer Johann Palisa. Following Palisa's death in 1925, this asteroid was named for a "happy or contented mind"; qualities associated with the discoverer.
Photometric observations of this asteroid collected during 2010 show a rotation period of 10.052 ± 0.001 hours with a brightness variation of 0.65 ± 0.03 magnitude.