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Dwarf Planets and Asteroids » 

Asteroid 17 Thetis

Below the horizon.  Rise: 9:36 | Tran: 15:45 | Set: 21:54
Alt: -33.03°   Az: 332.47°   Direction: North-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 DĂĽsseldorf. 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 in the constellation of Cetus, at a distance of 464,421,989.0 kilometers from Earth. The current Right Ascension is 01h 08m 37s and the Declination is +02° 05’ 54” (apparent coordinates). The magnitude of Asteroid 17 Thetis is 13.33 (data provided by JPL Horizons).

Finder Charts

Map showing Asteroid 17 Thetis in Cetus on February, 10 2025. Field of view: 50x30 degrees
View interactive star map
Sky map showing Asteroid 17 Thetis in Cetus on February, 10 2025. Field of view: 15x9 degrees. View in interactive sky chart

High 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: 01h 07m 20s
Dec: +01° 57’ 53”
Deep sky finder chart for Asteroid 17 Thetis. Field of view: 60x40 arcmins. View in deep sky object tracker

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.

Celestial Coordinates

Apparent

01h 08m 37s
+02° 05’ 54”
10h 28m 44s
11h 37m 22s

J2000

01h 07m 20s
+01° 57’ 53”

Additional Information

Cetus
13.33

Rise and Set Times

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

Azimuth: 87.9°
Max altitude: 40.7°
Azimuth: 272.2°
  • 17 Thetis is below the horizon from Greenwich, UK.
  • Given its current magnitude, 17 Thetis is visible with the help of a telescope having an aperture of 6 inches (150mm) 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.

Distance from Earth

The distance of Asteroid 17 Thetis from Earth is currently 464,421,989.0 kilometers, equivalent to 3.1044692470 Astronomical Units. Light takes 25m 49.145s to travel from Asteroid 17 Thetis and arrive to us.

464,421,989.0
3.1044692470
25m 49.145s

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

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
167,645,665
1.120642

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

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

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

Orbit Visualization

Orbit Diagram of Asteroid 17 Thetis
View Asteroid 17 Thetis in the 3D Solar System Simulator

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

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. Apparent celestial coordinates are provided.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2025 Feb 03 00h 59m 24s +01° 00’ 28” 13.30 Cetus
2025 Feb 04 01h 00m 41s +01° 09’ 39” 13.30 Cetus
2025 Feb 05 01h 01m 58s +01° 18’ 52” 13.31 Cetus
2025 Feb 06 01h 03m 16s +01° 28’ 04” 13.31 Cetus
2025 Feb 07 01h 04m 34s +01° 37’ 18” 13.32 Cetus
2025 Feb 08 01h 05m 52s +01° 46’ 32” 13.32 Cetus
2025 Feb 09 01h 07m 11s +01° 55’ 46” 13.33 Cetus
2025 Feb 10 01h 08m 30s +02° 05’ 02” 13.33 Cetus
2025 Feb 11 01h 09m 49s +02° 14’ 18” 13.34 Cetus
2025 Feb 12 01h 11m 09s +02° 23’ 34” 13.34 Cetus
2025 Feb 13 01h 12m 29s +02° 32’ 50” 13.35 Cetus
2025 Feb 14 01h 13m 50s +02° 42’ 07” 13.35 Cetus
2025 Feb 15 01h 15m 11s +02° 51’ 24” 13.36 Pisces
2025 Feb 16 01h 16m 32s +03° 00’ 41” 13.36 Pisces

Additional Resources