Skip to content
Public Universe
Comet

Arai

Add to an observing list or journal →

C/1991 A2 (Arai)

Arai is a comet in the Comet orbit class. Its orbit takes it from 1.43 AU to 305.8 AU from the Sun; one orbit takes 1,904 years. Orbit from the JPL solution of 15 April 2021.

Where is it now

Distance from Sun
57.259 AU
True anomaly
163.56°
Distance from Earth
57.548 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 Arai — 57.259 AU from the Sun Arai
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Arai is 57.548 AU from Earth today (8.0 light-hours).

In the sky

Right ascension
18h 32m 06s
Declination
+12° 56′ 34″
Constellation
Hercules
Distance from Earth
57.56 AU
Elongation from the Sun
72.02° — 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
153.617 AU
Eccentricity
0.9907
Inclination
70.98°
Orbital period
1,904 years
Perihelion
1.434 AU
Aphelion
305.8 AU
Longitude of ascending node
115.52°
Argument of periapsis
337.64°
Epoch · J2000
2448277.5
Orbit class · COM
Comet
Earth MOID · 192.2 LD
0.4938 AU
Tisserand (Jupiter)
0.517

Orbit quality

Observations used
110
Data arc
80 days
First observed
23 December 1990
Last observed
13 March 1991
Residual RMS
0.71 ″
Solution · Otto Matic
15 April 2021

Visual & observation

Absolute magnitude (H)
6.4
Total magnitude M₁ · K₁ 32
6.4

Discovery & classification

Also known as 1991 A2

Named

Sources