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Comet Near-Earth

Leonard

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P/2017 Y3 (Leonard)

Where is it now

Distance from Sun
16.025 AU
True anomaly
167.82°
Distance from Earth
15.114 AU
As of
24 October 2026

Two-body Kepler propagation — accurate to ~0.1% for major planets over decades, less so for highly-perturbed bodies. Use JPL Horizons for high precision.

Sun Earth — 0.994 AU from the Sun Earth Leonard — 16.025 AU from the Sun Leonard
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Leonard is 15.114 AU from Earth today (2.1 light-hours).

In the sky

Right ascension
02h 09m 17s
Declination
-12° 20′ 35″
Constellation
Cetus
Distance from Earth
15.12 AU
Elongation from the Sun
155.46° — well clear of the Sun

Visible from both hemispheres.

From your location

See how high it is right now, whether it is up after civil twilight, and when it rises and sets where you are.

How do I find my coordinates?

Google Maps on a computer

  1. Right-click the spot where you'll be observing.
  2. The first line of the menu is the coordinates, e.g. 51.50722, -0.12758 — click it and they're copied.
  3. Paste them above.

Google Maps on a phone

  1. Press and hold the spot to drop a pin.
  2. The coordinates appear in the search bar (or on the pin's card) — tap to copy, then paste above.

A full Google Maps link works too, but the short maps.app.goo.gl share links don't carry coordinates — copy the numbers instead. We round to about a kilometre; that's all the sky calculation needs.

Know your what3words address? Paste it, e.g. ///filled.count.soap. This is optional — the three words are sent to what3words to convert them, and we don't store the address or the result.

Your location stays in your browser and is sent only for this calculation. Using a what3words address is optional; if you do, the three words go to what3words to be converted and we don't record them. Set a location first, then you can save an email alert for this object. See our privacy policy.

Two-body approximation, good to about a degree for the planets — enough to find the constellation and know whether it is up.

Orbital elements

Semi-major axis
9.865 AU
Eccentricity
0.8707
Inclination
27.59°
Orbital period
30.98 years
Perihelion
1.275 AU
Aphelion
18.454 AU
Longitude of ascending node
153.87°
Argument of periapsis
67.53°
Epoch · J2000
2458169.5
Orbit class · HTC
Halley-type comet
Earth MOID · 191.1 LD
0.4911 AU
Tisserand (Jupiter)
1.728

Orbit quality

Orbit reasonably well determined (uncertainty code 4).

Observations used
93
Data arc
265 days
First observed
26 December 2017
Last observed
17 September 2018
Residual RMS
0.64 ″
Solution · Otto Matic
15 April 2021

Visual & observation

Absolute magnitude (H)
16.5
Total magnitude M₁ · K₁ 11
16.5

Discovery & classification

Also known as 2017 Y3

Near-Earth Object Named

Close approaches 1 on record

When (UTC) Body Distance Lunar distances Relative speed
2140-05-29 04:49:00 Juptr 1.8075 AU 703.4 LD 11.4 km/s

Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.

Sources