909 Ulla

Also known as (909) Ulla, Ulla

outer main-belt asteroid

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: K. Reinmuth
Discovery site: Heidelberg Obs.
Discovery date: 7 February 1919
Pronunciation: German: [ ˈʊlaː ] , Classically: / ˈ ʌ l ə /
Named after: Ulla Ahrens , (observatory donor)
Alternative designations: 1919 FA · 1936 SJ, 1949 OF 1 · 1949 PW, 1966 BU · 1966 DM, A912 CA · A919 CA
Minor planet category: main-belt · ( outer ) , Ulla · Cybele
Observation arc: 100.99 yr (36,886 d)
Aphelion: 3.8633 AU
Perihelion: 3.2217 AU
Semi major axis: 3.5425 AU
Orbital period sidereal: 6.67 yr (2,435 d)
Mean anomaly: 180.34 °
Mean motion: 0° 8 52.08 / day
Inclination: 18.797°
Longitude of ascending node: 146.35°
Argument of perihelion: 232.64°
Mean diameter: 113.13 ± 1.48 km 116.44 ± 2.4 km

via Wikipedia infobox

Wikidata facts

Diameter: 116.44
Orbital period: 2436.409816636143
Image: 909 Ulla orbit on 01 Jan 2009.png

Show 15 more facts

provisional designation: A919 CA
time of discovery or invention: 1919-02-07
orbital inclination: 18.80724536052427
albedo: 0.0343
rotation period: 8.7155
Commons category: 909 Ulla
absolute magnitude: 8.76
orbital eccentricity: 0.09431890134408452
semi-major axis of an orbit: 3.54351772265884
periapsis: 3.209297024164366
apoapsis: 3.877738421153315
longitude of ascending node: 145.9944919531775
argument of periapsis: 230.0995615111633
mean anomaly: 118.3777567623635
time of periapsis: 2460199.3424204243

Sources (3)

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Article

909 Ulla is a large and dark asteroid from the outermost regions of the asteroid belt, that measures approximately 116 kilometers (72 miles) in diameter. It is the parent body and namesake of the Ulla family, which belongs to the larger group of Cybele asteroids. It was discovered on 7 February 1919, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany. The X-type asteroid has a rotation period of 8.7 hours and a notably low value for its Jupiter Tisserand's parameter. It was named after Ulla Ahrens, daughter of a friend of the discoverer.

Orbit and classification