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A Complete Guide to the Solar System and the Night Sky
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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 7:44  
clear_day Transit: 11:48  
SunsetSet: 15:51 south
sleep NighttimeWhat's Visible Now?
Dwarf Planets and Asteroids » 

Asteroid 17 Thetis

Altitude: -51.7°   Azimuth: 310.1°   Direction: North-West

Asteroid 17 Thetis is a large main-belt asteroid that was discovered on April 17, 1852, by the German astronomer Robert Luther at Bilk Observatory in Düsseldorf. It is named after Thetis, a sea goddess in Greek mythology who is the mother of Achilles. Thetis has an estimated diameter of about 90 kilometers and orbits the Sun at an average distance of about 2.4 astronomical units (AU), with an orbital period of about 3.6 years. Its rotation period is estimated to be about 6.4 hours. Little is known about the surface features or composition of Thetis, but its relatively low density suggests that it may be a C-type asteroid, composed of carbonaceous materials.

Asteroid 17 Thetis is currently in the constellation of Sagittarius.

The current Right Ascension of Asteroid 17 Thetis is 17h 50m 42s and the Declination is -21° 27’ 11” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom edit_location_alt). The current magnitude of Asteroid 17 Thetis is 12.47 (JPL).

17h 50m 42s
-21° 27’ 11”

Today's rise, transit and set times of Asteroid 17 Thetis from Greenwich, United Kingdom edit_location_alt (all times relative to the local timezone Europe/London):

Azimuth: 111.4°
Max altitude: 17.1°
Azimuth: 248.6°
  • 17 Thetis is below the horizon from Greenwich, United Kingdom edit_location_alt.
  • Given its current magnitude, 17 Thetis 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 17 Thetis Position and Finder Charts

Below we provide Asteroid 17 Thetis 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 17 Thetis in Sagittarius on December,03 2023
Map showing Asteroid 17 Thetis in Sagittarius on December, 03 2023
Field of view: 50x30 degrees
View fullscreen
Finder chart of 17 Thetis
Map showing Asteroid 17 Thetis in Sagittarius on December, 03 2023
Field of view: 10x6 degrees
View fullscreen

Higher precision deep sky finder chart, 60 arcmin wide, showing where Asteroid 17 Thetis is right now. Click on the image to see a more detailed fullscreen tracker view.

17 Thetis
RA: 17h 50m 42s
Dec: -21° 27’ 11”
Deep sky finder chart for Asteroid 17 Thetis
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Asteroid 17 Thetis?, a page that provides all the information needed to find Asteroid 17 Thetis in the sky and additional links to sky charts.

Asteroid 17 Thetis Distance from Earth

The distance of Asteroid 17 Thetis from Earth is currently 460,194,311 kilometers, equivalent to 3.076209 Astronomical Units. Light takes 25 minutes and 35.0430 seconds to travel from Asteroid 17 Thetis and arrive to us.

25 minutes and 35.0430 seconds

The following chart shows the distance of Asteroid 17 Thetis 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 17 Thetis 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 17 Thetis from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest Approach of Asteroid 17 Thetis to Earth

Between 1 January 1900 and 31 December 2099, the closest approach of Asteroid 17 Thetis to Earth happens on Wed Jun 15 1938 at a distance of 1.120642 Astronomical Units, or 167,645,665 kilometers:

Wed Jun 15 1938

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

Asteroid 17 Thetis Brightness and Light Curve

The following chart is the predicted light curve (visual magnitude as a function of time) of Asteroid 17 Thetis, 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 17 Thetis as a function of time

Asteroid 17 Thetis Orbital Elements

The following table lists the orbital elements of Asteroid 17 Thetis at epoch 24 February 2023 00:00 UTC (JD: 2460000.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.13257020
Orbit inclination i 5.59200088°
Perihelion distance q 2.14367299 AU
320,688,915 km
Aphelion distance Q 2.79891255 AU
418,711,358 km
Semi-major axis a 2.47129277 AU
369,700,137 km
Orbital period period 3.8850 years
1,419.0076 days
Date of perihelion transit Tp 2023-Oct-22 21:25:10
2,460,240.3925 JD
Next perihelion transit 2027-Sep-10 21:36
2,461,659.4001 JD
Argument of perihelion peri 135.72403018034°
Longitude of the ascending node node 125.53993295224°
Mean anomaly M 299.13965437649°
Mean motion n 0.25369843°/day

Visualization of Asteroid 17 Thetis Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Asteroid 17 Thetis with respect of the Sun and the orbits of the major planets. The position of Asteroid 17 Thetis 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 17 Thetis
View Asteroid 17 Thetis in the 3D Solar System Simulator

Asteroid 17 Thetis Physical Data

The following shows the known values of the most important physical parameters of Asteroid 17 Thetis. Source: JPL Small-Body Database

Physical Parameter Value Relative to Earth
Diameter 90.04 km 0.0071
Sideral Rotation 12.2705 hours 0.5127
Absolute Magnitude 7.76
Geometric Albedo 0.1715

Asteroid 17 Thetis 15 Days Ephemeris

The following table lists the ephemerides of Asteroid 17 Thetis computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Asteroid 17 Thetis in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2023 Nov 26 17h 32m 15s -21° 08’ 31” 12.52 Ophiucus
2023 Nov 27 17h 34m 33s -21° 11’ 20” 12.51 Ophiucus
2023 Nov 28 17h 36m 52s -21° 13’ 59” 12.51 Ophiucus
2023 Nov 29 17h 39m 11s -21° 16’ 32” 12.50 Ophiucus
2023 Nov 30 17h 41m 30s -21° 18’ 56” 12.49 Ophiucus
2023 Dec 01 17h 43m 50s -21° 21’ 14” 12.49 Sagittarius
2023 Dec 02 17h 46m 09s -21° 23’ 21” 12.48 Sagittarius
2023 Dec 03 17h 48m 29s -21° 25’ 23” 12.48 Sagittarius
2023 Dec 04 17h 50m 48s -21° 27’ 15” 12.47 Sagittarius
2023 Dec 05 17h 53m 08s -21° 28’ 59” 12.46 Sagittarius
2023 Dec 06 17h 55m 27s -21° 30’ 37” 12.46 Sagittarius
2023 Dec 07 17h 57m 47s -21° 32’ 04” 12.45 Sagittarius
2023 Dec 08 18h 00m 09s -21° 33’ 24” 12.44 Sagittarius
2023 Dec 09 18h 02m 29s -21° 34’ 37” 12.43 Sagittarius