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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 7:48  
clear_day Transit: 11:49  
SunsetSet: 15:50 south
sunny DaytimeWhat's Visible Now?
Dwarf Planets and Asteroids » 

Asteroid 20 Massalia

Altitude: -11.8°   Azimuth: 110.2°   Direction: East-South-East

Asteroid 20 Massalia was discovered by astronomer Annibale de Gasparis on September 19, 1852. It is named after the ancient Greek city of Massalia, which is now modern-day Marseille, France. Massalia is a relatively large and bright asteroid, with a diameter of about 146 kilometers. It is classified as an S-type asteroid, meaning that it is composed primarily of silicate rock and metal. Massalia has a relatively short rotation period of just over 6 hours and orbits the Sun every 4.3 years at an average distance of 2.41 astronomical units (AU).

Asteroid 20 Massalia is currently in the constellation of Sagittarius.

The current Right Ascension of Asteroid 20 Massalia is 19h 16m 40s and the Declination is -21° 42’ 37” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom edit_location_alt). The current magnitude of Asteroid 20 Massalia is 12.14 (JPL).

19h 16m 40s
-21° 42’ 37”

Today's rise, transit and set times of Asteroid 20 Massalia from Greenwich, United Kingdom edit_location_alt (all times relative to the local timezone Europe/London):

Azimuth: 111.7°
Max altitude: 16.8°
Azimuth: 248.3°
  • 20 Massalia is below the horizon from Greenwich, United Kingdom edit_location_alt.
  • Given its current magnitude, 20 Massalia is visible with the help of a telescope having an aperture of 4 inches (100mm) or more.
  • Go to interactive sky chart

If you need to access this information frequently for your observations, you can create a simple customized Quick Access page, so that you can easily bookmark it in your browser favorites or add a shortcut to your mobile phones' home screen.

Available Resources

Asteroid 20 Massalia Position and Finder Charts

Below we provide Asteroid 20 Massalia finder charts showing where the object is right now in the sky with respect to the brightest stars. The first finder chart has a field of view of 50 degrees, while the second one has a field of view of 10 degrees. Click on each finder chart to access a full screen interactive Online Planetarium.

Finder chart of 20 Massalia in Sagittarius on December,06 2023
Map showing Asteroid 20 Massalia in Sagittarius on December, 06 2023
Field of view: 50x30 degrees
View fullscreen
Finder chart of 20 Massalia
Map showing Asteroid 20 Massalia in Sagittarius on December, 06 2023
Field of view: 10x6 degrees
View fullscreen

Higher precision deep sky finder chart, 60 arcmin wide, showing where Asteroid 20 Massalia is right now. Click on the image to see a more detailed fullscreen tracker view.

20 Massalia
RA: 19h 16m 40s
Dec: -21° 42’ 37”
Deep sky finder chart for Asteroid 20 Massalia
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Asteroid 20 Massalia?, a page that provides all the information needed to find Asteroid 20 Massalia in the sky and additional links to sky charts.

Asteroid 20 Massalia Distance from Earth

The distance of Asteroid 20 Massalia from Earth is currently 522,857,667 kilometers, equivalent to 3.495088 Astronomical Units. Light takes 29 minutes and 4.0654 seconds to travel from Asteroid 20 Massalia and arrive to us.

29 minutes and 4.0654 seconds

The following chart shows the distance of Asteroid 20 Massalia from Earth as a function of time. In the chart the distance data is measured in Astronomical Units and sampled with an interval of 1 day.

Chart of the distance of Asteroid 20 Massalia from Earth in Astronomical Units (au)

The value of the reported distance might be somewhat inaccurate around the times of closest approach for objects passing extremely close to Earth. The value of the distance of 20 Massalia from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest Approach of Asteroid 20 Massalia to Earth

Between 1 January 1900 and 31 December 2099, the closest approach of Asteroid 20 Massalia to Earth happens on Mon Jan 6 2048 at a distance of 1.077062 Astronomical Units, or 161,126,212 kilometers:

Mon Jan 6 2048

NOTE: values for the closest approach are computed with a sampling interval of 1 day.

Asteroid 20 Massalia Brightness and Light Curve

The following chart is the predicted light curve (visual magnitude as a function of time) of Asteroid 20 Massalia, according to the most recent ephemerides data. Magnitude data is sampled with a 2 days interval and there might be inaccuracies for objects changing brightness very rapidly during the course of a few days. For comets there could be large discrepancies between the observed and predicted brightness because of their highly dynamic behaviour.

Chart of the magnitude of Asteroid 20 Massalia as a function of time

Asteroid 20 Massalia Orbital Elements

The following table lists the orbital elements of Asteroid 20 Massalia at epoch 24 February 2023 00:00 UTC (JD: 2460000.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.14328810
Orbit inclination i 0.70919118°
Perihelion distance q 2.06345443 AU
308,688,390 km
Aphelion distance Q 2.75369454 AU
411,946,840 km
Semi-major axis a 2.40857448 AU
360,317,615 km
Orbital period period 3.7381 years
1,365.3329 days
Date of perihelion transit Tp 2021-Nov-04 02:43:02
2,459,522.6132 JD
Next perihelion transit 2025-Jul-31 10:42
2,460,887.9461 JD
Argument of perihelion peri 257.50682680841°
Longitude of the ascending node node 205.9677482734°
Mean anomaly M 126.00534306121°
Mean motion n 0.26367196°/day

Visualization of Asteroid 20 Massalia Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Asteroid 20 Massalia with respect of the Sun and the orbits of the major planets. The position of Asteroid 20 Massalia and the planets along their orbits in this diagram accurately represents the current configuration of the objects in the Solar System. This is an experimental feature and it requires a WebGL enabled browser. Please provide us feedback!

Orbit Diagram of Asteroid 20 Massalia
View Asteroid 20 Massalia in the 3D Solar System Simulator

Asteroid 20 Massalia Physical Data

The following shows the known values of the most important physical parameters of Asteroid 20 Massalia. Source: JPL Small-Body Database

Physical Parameter Value Relative to Earth
Diameter 145.5 km 0.0114
Sideral Rotation 8.0980 hours 0.3383
Absolute Magnitude 6.5
Geometric Albedo 0.2096

Asteroid 20 Massalia 15 Days Ephemeris

The following table lists the ephemerides of Asteroid 20 Massalia computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Asteroid 20 Massalia in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2023 Nov 29 19h 04m 27s -22° 02’ 35” 12.15 Sagittarius
2023 Nov 30 19h 06m 06s -22° 00’ 06” 12.15 Sagittarius
2023 Dec 01 19h 07m 45s -21° 57’ 33” 12.15 Sagittarius
2023 Dec 02 19h 09m 24s -21° 54’ 56” 12.15 Sagittarius
2023 Dec 03 19h 11m 03s -21° 52’ 14” 12.14 Sagittarius
2023 Dec 04 19h 12m 42s -21° 49’ 27” 12.14 Sagittarius
2023 Dec 05 19h 14m 22s -21° 46’ 36” 12.14 Sagittarius
2023 Dec 06 19h 16m 02s -21° 43’ 41” 12.14 Sagittarius
2023 Dec 07 19h 17m 44s -21° 40’ 41” 12.14 Sagittarius
2023 Dec 08 19h 19m 23s -21° 37’ 36” 12.13 Sagittarius
2023 Dec 09 19h 21m 05s -21° 34’ 27” 12.13 Sagittarius
2023 Dec 10 19h 22m 45s -21° 31’ 14” 12.13 Sagittarius
2023 Dec 11 19h 24m 26s -21° 27’ 56” 12.13 Sagittarius
2023 Dec 12 19h 26m 08s -21° 24’ 34” 12.12 Sagittarius