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Comet Near-Earth

Schwassmann-Wachmann

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73P/Schwassmann-Wachmann 3-BT

Where is it now

Distance from Sun
4.161 AU
True anomaly
207.85°
Distance from Earth
4.409 AU
As of
11 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.

Orbit of Mercury Orbit of Venus Orbit of Mars Sun Earth — 0.998 AU from the Sun Earth Schwassmann-Wachmann — 4.161 AU from the Sun Schwassmann-Wachmann
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Schwassmann-Wachmann is 4.409 AU from Earth today (36.7 light-minutes).

In the sky

Right ascension
08h 56m 46s
Declination
+25° 21′ 52″
Constellation
Cancer
Distance from Earth
4.4 AU
Elongation from the Sun
69.73° — well clear of the Sun

Favours the northern hemisphere; low or below the horizon from far south.

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
3.092 AU
Eccentricity
0.6856
Inclination
11.24°
Orbital period
5.44 years
Perihelion
0.972 AU
Aphelion
5.212 AU
Longitude of ascending node
69.66°
Argument of periapsis
199.35°
Epoch · J2000
2457821.5
Orbit class · JFc
Jupiter-family comet (P < 20 y)
Earth MOID · 5.5 LD
0.0143 AU
Tisserand (Jupiter)
2.784

Orbit quality

Orbit poorly determined (uncertainty code 6).

Observations used
353
Data arc
250 days
First observed
10 February 2017
Last observed
18 October 2017
Residual RMS
0.91 ″
Solution · Otto Matic
15 April 2021

Visual & observation

Absolute magnitude (H)
13.3
Total magnitude M₁ · K₁ 15.3
13.3

Discovery & classification

Also known as 73P-BT

Near-Earth Object Named

Close approaches 5 on record

Flyby geometry
Ecliptic flyby of Schwassmann-Wachmann at 2033-04-12 15:10 UTC Top-down view of the ecliptic, Earth at the centre, for the 2033-04-12 15:10 UTC close approach of Schwassmann-Wachmann. Catalogue miss distance 127.4 LD · 4.9 × 10⁷ km. The curve is the geocentric path from 2033-04-09 to 2033-04-15, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is north of the ecliptic. The path is approximate: a two-body Kepler propagation of the catalogue orbital elements, not a numerical integration. The Moon’s position is approximate. The inset is a heliocentric view and is approximate. approximate Sun 127.4 LD · 4.9 × 10⁷ km 2033-04-12 15:10 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2033-04-12 15:10 UTC close approach of Schwassmann-Wachmann. Catalogue miss distance 127.4 LD · 4.9 × 10⁷ km. The curve is the geocentric path from 2033-04-09 to 2033-04-15, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is north of the ecliptic. The path is approximate: a two-body Kepler propagation of the catalogue orbital elements, not a numerical integration. The Moon’s position is approximate. The inset is a heliocentric view and is approximate.

When (UTC) Body Distance Lunar distances Relative speed
2033-04-12 15:10:00 Earth 0.3274 AU 127.4 LD 23.2 km/s
2037-05-03 11:36:00 Juptr 1.6884 AU 657.1 LD 12 km/s

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

Sources