Menu

Parthenope — Asteroid in Leo

11 Parthenope

Asteroid Leo Visible
Star Map 3D Solar System
+ List + Plan

Properties

Magnitude 9.5
Type: Asteroid
Distance: 2.453 AU
Orbital Period: 1403.4 days
Diameter: 143 km
Greek siren who lured sailors to their deaths in Homer's Odyssey; S-type; one of the brightest minor planets at opposition (typical mag 9.5).

Position & Identifiers

RA 10h 13m 27.3s
Dec +15° 22' 39.1"
Constellation Leo
Catalog Parthenope

Physical Properties

Diameter 143 km
Mass 3.8e18 kg
Albedo 0.19 (19% reflected)
Rotation 13.7 hours
Angular Size 0.1″ (current)

Orbital Properties

Semi-major Axis 2.4532 AU (367.0 million km)
Eccentricity 0.1005
Inclination 4.64°
Orbital Period 3.84 years
Distance 2.146 AU (17.9 light-min)
Elongation 109.9° Good

Brightness Forecast (next 12 months)

Apparent magnitude as Earth–asteroid distance changes through the year. The peak marks the brightest moment in the window — usually around opposition, when the asteroid is closest and fully illuminated.

10.011.0MayJunJulAugSepOctNovDecJanFebMarAprpeak 9.5 · 30 AprnowMagnitude↑ brighter

Computed from JPL orbital elements via m = H + 5·log10(r·Δ). Phase-function correction is omitted, so curves trace distance variation only — accurate within a few tenths for main-belt asteroids; coarse for fast-moving NEOs near Earth.

Observing Tips

Best Months June , July , August
Visibility Telescope
Where to Look In asteroid belt
Notes Greek siren who lured sailors to their deaths in Homer's Odyssey; S-type; one of the brightest minor planets at opposition (typical mag 9.5).

Discovery

Discovered by Annibale de Gasparis
Date 1850-05-11

Current Ephemeris

2.146
AU from Earth
321.1M
km
0.1
Angular Size
110°
Elongation

How easy to spot?

Sign in and configure your equipment and default location to see a personalized row.
Telescope Bortle 3 Bortle 4 Bortle 5
80mm refr. Medium+ Medium Medium
150mm Newt. Easy Easy Medium+
C8 203mm Easy Easy Easy
Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

Easy on Seestar S50

Visibility

Set a location in User Settings to see visibility data.

Community Photos (1)

Rendered preview of Parthenope from the Nightbase orrery, lit from the current Sun direction with the terminator visible.

Rendered preview of Parthenope from the Nightbase orrery, lit from the current Sun direction with the terminator visible.

Credit: Nightbase orrery render.

Skybred Apr 27, 2026

}