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Asteroid Near-Earth Potentially hazardous

137427

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137427 (1999 TF211)

Where is it now

Distance from Sun
2.025 AU
True anomaly
246.26°
Distance from Earth
1.268 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 137427 — 2.025 AU from the Sun 137427
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 137427 is 1.268 AU from Earth today (10.5 light-minutes).

In the sky

Right ascension
00h 42m 36s
Declination
+60° 57′ 36″
Constellation
Cassiopeia
Distance from Earth
1.26 AU
Elongation from the Sun
126.25° — 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
2.439 AU
Eccentricity
0.6119
Inclination
39.51°
Orbital period
3.81 years
Perihelion
0.947 AU
Aphelion
3.932 AU
Longitude of ascending node
347.9°
Argument of periapsis
162.4°
Epoch · J2000
2461200.5
Orbit class · APO
Apollo
Earth MOID · 11.0 LD
0.0283 AU
Tisserand (Jupiter)
2.969

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
927
Data arc
27 years
First observed
6 October 1999
Last observed
6 October 2026
Residual RMS
0.57 ″
Solution · Otto Matic
7 October 2026

Visual & observation

Absolute magnitude (H)
15.28

Discovery & classification

Discovered by
LINEAR
Discovery date
15 October 1999
Discovery site
Socorro

Also known as 1999 TF211

Apollo Near-Earth Object Potentially Hazardous Asteroid

Close approaches 16 on record

Flyby geometry
Ecliptic flyby of 137427 at 2065-03-03 19:20 UTC Top-down view of the ecliptic, Earth at the centre, for the 2065-03-03 19:20 UTC close approach of 137427. Catalogue miss distance 36.7 LD · 1.41 × 10⁷ km. The curve is the geocentric path from 2065-02-28 to 2065-03-06, 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 36.7 LD · 1.41 × 10⁷ km 2065-03-03 19:20 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2065-03-03 19:20 UTC close approach of 137427. Catalogue miss distance 36.7 LD · 1.41 × 10⁷ km. The curve is the geocentric path from 2065-02-28 to 2065-03-06, 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
2065-03-03 19:20:00 Earth 0.0943 AU 36.7 LD 24.7 km/s
2093-07-29 07:04:00 Juptr 1.861 AU 724.2 LD 9.8 km/s
2103-02-28 02:09:00 Earth 0.1775 AU 69.1 LD 24.2 km/s
2105-03-31 02:30:00 Juptr 1.2694 AU 494.0 LD 8.8 km/s
2116-11-22 14:50:00 Juptr 1.232 AU 479.5 LD 9.4 km/s
2128-06-27 06:48:00 Juptr 1.7906 AU 696.8 LD 11.1 km/s
2179-03-02 16:17:00 Earth 0.1298 AU 50.5 LD 24.5 km/s
2198-03-05 21:13:00 Earth 0.0693 AU 27.0 LD 24.3 km/s
2200-03-10 20:21:00 Juptr 1.3492 AU 525.1 LD 9 km/s

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

Sources