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Asteroid Near-Earth Potentially hazardous

Moshup

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66391 Moshup (1999 KW4)

Where is it now

Distance from Sun
0.964 AU
True anomaly
199.4°
Distance from Earth
1.608 AU
As of
15 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 — 0.997 AU from the Sun Earth Moshup — 0.964 AU from the Sun Moshup
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Moshup is 1.608 AU from Earth today (13.4 light-minutes).

In the sky

Right ascension
15h 42m 56s
Declination
-07° 47′ 32″
Constellation
Libra
Distance from Earth
1.61 AU
Elongation from the Sun
33.97° — near the Sun — look low at dusk or dawn

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
0.642 AU
Eccentricity
0.6884
Inclination
38.88°
Orbital period
188.1 days
Perihelion
0.2 AU
Aphelion
1.085 AU
Longitude of ascending node
244.9°
Argument of periapsis
192.65°
Epoch · J2000
2461200.5
Orbit class · ATE
Aten
Earth MOID · 5.2 LD
0.0132 AU
Tisserand (Jupiter)
8.497

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
3,871
Data arc
27.89 years
First observed
29 May 1998
Last observed
20 April 2026
Residual RMS
0.31 ″
Solution · Otto Matic
20 April 2026

Physical properties

Mean radius
0.66 km
Density
1.974 g/cm³
Rotation period
2.76 hours
Shape · km
1.532 x 1.495 x 1.347

Visual & observation

Absolute magnitude (H)
16.64
Spectral type (SMASS)
S:

Discovery & classification

Discovered by
LINEAR
Discovery date
20 May 1999
Discovery site
Socorro

Moshup was a giant who lived in the coastal areas of New England, according to Native American legends, and was responsible for a variety of geologic features. As a way of maintaining balance, he married Granny Squannit, a leader of the Makiawasug, or Little People, who lived nearby. Squannit was a medicine woman of the Makiawasug who married the giant Moshup. Bad weather was attributed to times when the pair would argue. Moshup is the name of the primary, Squannit that for the satellite.

Also known as 66391 · 1999 KW4

Aten Near-Earth Object Named Potentially Hazardous Asteroid

Close approaches 63 on record

Flyby geometry
Ecliptic flyby of Moshup at 2034-06-02 17:40 UTC Top-down view of the ecliptic, Earth at the centre, for the 2034-06-02 17:40 UTC close approach of Moshup. Catalogue miss distance 76.5 LD · 2.94 × 10⁷ km. The curve is the geocentric path from 2034-05-30 to 2034-06-05, 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 a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate. Sun 76.5 LD · 2.94 × 10⁷ km 2034-06-02 17:40 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2034-06-02 17:40 UTC close approach of Moshup. Catalogue miss distance 76.5 LD · 2.94 × 10⁷ km. The curve is the geocentric path from 2034-05-30 to 2034-06-05, 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 a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate.

JPL Horizons

When (UTC) Body Distance Lunar distances Relative speed
2034-06-02 17:40:00 Earth 0.1966 AU 76.5 LD 19.9 km/s
2035-05-29 05:59:00 Earth 0.1122 AU 43.7 LD 19.7 km/s
2036-05-25 13:43:00 Earth 0.0155 AU 6.0 LD 20.8 km/s
2037-05-26 03:46:00 Earth 0.1125 AU 43.8 LD 23.4 km/s
2052-05-30 23:57:00 Earth 0.1584 AU 61.6 LD 19.7 km/s
2053-05-27 03:07:00 Earth 0.0678 AU 26.4 LD 20 km/s
2054-05-25 21:17:00 Earth 0.0457 AU 17.8 LD 21.8 km/s
2055-05-27 22:33:00 Earth 0.1718 AU 66.9 LD 25 km/s
2069-06-02 17:17:00 Earth 0.1979 AU 77.0 LD 19.9 km/s
2070-05-29 06:06:00 Earth 0.1144 AU 44.5 LD 19.7 km/s

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

Sources