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
Small body data
(1541) Estonia
- Orbit class
- Main-belt
- Semi-major axis
- 2.770 AU
- Eccentricity
- 0.067
- Inclination
- 4.870 °
- Absolute magnitude
- 11.550 H
via Minor Planet Center
Key facts
- Discovered by
- Y. Väisälä
- Discovery site
- Turku Observatory
- Discovery date
- 12 February 1939
- Named after
- Estonia , ( Baltic country )
- Alternative designations
- 1939 CK · 1930 FE, 1930 FV · 1950 RG 1 , 1950 SR · 1959 RF 1 , A916 GE · A923 VE
- Minor planet category
- main-belt · ( middle )
- Observation arc
- 93.57 yr (34,176 days)
- Aphelion
- 2.9610 AU
- Perihelion
- 2.5761 AU
- Semi major axis
- 2.7685 AU
- Orbital period sidereal
- 4.61 yr (1,683 days)
- Mean anomaly
- 346.22 °
- Mean motion
- 0° 12 50.4 / day
- Inclination
- 4.8750°
- Longitude of ascending node
- 1.4553°
- Argument of perihelion
- 192.84°
- Dimensions
- 19.53 ± 0.40 km , 20.15 km (derived) , 20.56 ± 6.71 km , 22.000 ± 0.342 km , 23.89 ± 1.35 km , 24.542 ± 0.096 km
- Synodic rotation period
- 10.1 ± 1.0 h
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Named after
- Estonia
- Followed by
- 1542 Schalén
- Follows
- 1540 Kevola
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 22.0
- Orbital period
- 1684.545369209231
Show 18 more facts
- discoverer or inventor
- Yrjö Väisälä
- site of astronomical discovery
- Iso-Heikkilä Observatory
- provisional designation
- A923 VE
- time of discovery or invention
- 1939-02-12
- orbital eccentricity
- 0.06801779675301907
- orbital inclination
- 4.867291790398478
- periapsis
- 2.582243202427886
- apoapsis
- 2.959157037687163
- semi-major axis of an orbit
- 2.770700120057524
- mean anomaly
- 271.0574205924613
- longitude of ascending node
- 1.281704762763461
- argument of periapsis
- 190.0916175263113
- absolute magnitude
- 11.57
- albedo
- 0.14
- rotation period
- 12.89
- asteroid spectral type
- X-type asteroid
- time of periapsis
- 2461416.6883618515
- epoch
- November 21, 2025
Sources (2)
via Wikidata · CC0
~3 min read
Encyclopedic overview
1541 Estonia (provisional designation 1939 CK) is an asteroid from the central regions of the asteroid belt, approximately 21 kilometers in diameter. It was discovered on 12 February 1939, by astronomer Yrjö Väisälä at the Iso-Heikkilä Observatory near Turku, Finland. The asteroid was named after the Baltic country of Estonia.
Orbit and classification
Excerpted from Wikipedia’s “1541 Estonia” article, available under the CC BY-SA 4.0 licence.