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
- Y. Väisälä
- Discovery site
- Turku Obs.
- Discovery date
- 22 October 1938
- Named after
- Seinäjoki (Finnish city)
- Alternative designations
- 1938 UB 1 · 1933 UR 1 , 1967 UW
- Minor planet category
- main-belt · ( outer ) , Brasilia
- Observation arc
- 78.62 yr (28,716 days)
- Aphelion
- 3.2435 AU
- Perihelion
- 2.4633 AU
- Semi major axis
- 2.8534 AU
- Orbital period sidereal
- 4.82 yr (1,760 days)
- Mean anomaly
- 123.44 °
- Mean motion
- 0° 12 16.2 / day
- Inclination
- 15.059°
- Longitude of ascending node
- 12.593°
- Argument of perihelion
- 48.805°
- Mean diameter
- 13.66 ± 3.61 km , 14.813 ± 0.070 km , 16.095 ± 0.070 km , 16.29 ± 0.20 km , 24.30 km (calculated)
- Synodic rotation period
- 4.32 ± 0.01 h , 4.328 159 ± 0.000 001 h
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Named after
- Seinäjoki
- Followed by
- Q140399
- Follows
- 1520 Imatra
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 14.813
- Orbital period
- 1757.455070629364
- Image
- 001521-asteroid shape model (1521) Seinäjoki.png
Show 18 more facts
- discoverer or inventor
- Yrjö Väisälä
- site of astronomical discovery
- Iso-Heikkilä Observatory
- provisional designation
- 1967 UW
- time of discovery or invention
- 1938-10-22
- orbital eccentricity
- 0.1402356076045749
- orbital inclination
- 15.02931132699835
- periapsis
- 2.450398158518141
- apoapsis
- 3.249763839796271
- semi-major axis of an orbit
- 2.850080999157206
- mean anomaly
- 16.53853188194509
- longitude of ascending node
- 12.40956049993403
- argument of periapsis
- 50.09743664451045
- absolute magnitude
- 12.01
- Commons category
- 1521 Seinäjoki
- albedo
- 0.205
- rotation period
- 4.32
- time of periapsis
- 2460919.7618702315
- epoch
- November 21, 2025
Sources (3)
via Wikidata · CC0
~3 min read
Encyclopedic overview
1521 Seinäjoki (provisional designation 1938 UB1) is a Brasilia asteroid from the outer region of the asteroid belt, approximately 14 kilometers in diameter. It was discovered on 22 October 1938, by Finnish astronomer Yrjö Väisälä at the southwestern Turku Observatory, Finland. The asteroid was later named after the Finnish city of Seinäjoki.
Orbit and classification
Excerpted from Wikipedia’s “1521 Seinäjoki” article, available under the CC BY-SA 4.0 licence.