At a glance
- Width
- 138 to 309 m
- about 1,118 bananas
- Speed
- 18.28 km/s
- 65,823 km/h · 40,900 mph
- Misses us by
- 98.9 lunar
- 38,051,109 km · 23,643,856 miles
- First spotted by us
- 13th November 2026
- 3 page views
How far is "close"?
Same gap, ranked against places you have heard of, on a log scale because the Sun is awkwardly far away.
How big is it, really?
NASA only estimates the width, so we show the biggest guess. Log scale again. Everest is just there to make everything else look reasonable.
How fast is it going?
Speed relative to Earth at closest approach. The International Space Station is the fastest thing most of us will ever stand under. This lot would lap it.
If it hit (it will not)
Rough impact energy at the biggest size estimate, assuming solid rock, in tonnes, kilotons and megatons of TNT, which is how everyone who has to do this maths measures it. Treat it as a ballpark. The point stands: no impact is scheduled.
Where it actually lives
A top-down view of the orbit, to scale, with Earth's and Mars's orbits for company. The tilt of the orbit is ignored, so treat the shape as right and the exact position as roughly right. The Sun is the orange dot in the middle.
- Orbit class
- APOApollo: crosses Earth's orbit, but spends most of its time further out than us. The most common troublemaker type.
- Year length
- 4.99 Earth years (1,823 days)One lap of the Sun. Your commute is shorter, and so is your patience.
- Eccentricity
- 0.813How squashed the orbit is. 0 is a perfect circle, 1 is "leaving". Very stretched. This rock commutes the long way round.
- Tilt
- 14.3°The angle of its orbit against the flat plane the planets share. Slightly tipsy.
- Closest to the Sun
- 0.55 AU82 million km. One AU is the distance from Earth to the Sun.
- Furthest from the Sun
- 5.29 AU792 million km. Jupiter's territory.
- Closest orbit-to-orbit gap
- 0.137 AUIf you only compare the two orbits, not where the planets are, they come within 53 lunar distances. The rock is rarely there at the same time as us, which is the entire reason we are still here.
- Observations used
- 84NASA has measured this one 84 times. It has been stalked thoroughly.
- Watched for
- 10.0 years2011-10-24 to 2021-11-07. Long enough to know it well.
- Orbit uncertainty
- 0 out of 90 means we know exactly where it is going. 9 means a shrug. Lower is better.
Is it actually hazardous?
This one fails at least one test, so it is not on the list. It is comfortably, boringly harmless.
Not on NASA's Sentry impact-risk watch list. No further action, no thoughts, head empty.
Its history with us
Every known pass this rock makes, 1900 to 2200. Dim dots are the past, green dots are still to come, the big orange ring is this one. The dashed line is the Moon's distance, so anything below it is closer than the Moon. Almost nothing is.
| Date | Miss distance | Speed |
|---|---|---|
| 16th November 1966 | 99.0 LD · 38,079,149 km | 17.8 km/s |
| 7th November 1971 | 57.7 LD · 22,192,257 km | 21.2 km/s |
| 14th November 1976 | 89.6 LD · 34,457,983 km | 18.2 km/s |
| 27th December 1981 | 160.7 LD · 61,786,374 km | 19.7 km/s |
| 15th January 1987 | 179.9 LD · 69,195,605 km | 23.6 km/s |
| 3rd January 1992 | 173.6 LD · 66,774,698 km | 21.8 km/s |
| 12th December 1996 | 150.3 LD · 57,781,956 km | 17.5 km/s |
| 18th November 2001 | 110.6 LD · 42,538,880 km | 17.0 km/s |
| 12th November 2006 | 84.5 LD · 32,487,592 km | 19.2 km/s |
| 6th November 2011 | 65.0 LD · 25,009,384 km | 21.6 km/s |
By the numbers
- Estimated mass
- 4.1 million tonnes to 46.4 million tonnesVolume of a sphere at NASA's smallest and largest width estimates, times 3,000 kg per cubic metre (typical rock). Real shapes are lumpier, so treat it as a ballpark.
- Swimming pools of rock
- 2,343 Olympic poolsSphere volume at the middle width estimate, divided by 2,500 cubic metres per Olympic pool.
- Impact energy, if it hit
- 166 megatons to 1,853 megatonsHalf mass times speed squared, at the small and large width estimates, converted to TNT (1 kiloton is 4.184 trillion joules). A rock this far away is not going to do this.
- Speed against escape velocity
- 1.6 timesIts speed relative to Earth, divided by the 11.186 km/s needed to leave Earth's gravity. It is travelling a lot faster than we can throw things.
- Speed against Earth in orbit
- 0.61 timesDivided by Earth's own orbital speed of 29.78 km/s around the Sun.
- Time to cross the UK
- 53.1 secondsLand's End to John o' Groats is about 970 km in a straight line. Divided by its speed.
- Time to fly the miss distance
- 24.1 daysThe miss distance divided by its speed. This is how long it needs to cover a gap of that size, which is a measure of how near or far the pass is.
- Light takes to cross the gap
- 126.9 secondsMiss distance divided by the speed of light.
- Width from brightness alone
- 138 to 309 mAstronomers estimate size from how bright an asteroid is (H 21.4) and how reflective it is. A shiny rock (albedo 0.25) is smaller than a dark one (0.05) for the same brightness. NASA's own estimate above uses the same idea.
- Laps of the Sun since first spotted
- 2.03,667 days of observation divided by its 1,823-day year.
- Known close approaches, 1900 to 2200
- 570 inside the Moon's orbit and 0 within ten lunar distances.
- Closest pass in that period
- 21.05 lunar distancesOn 1st May 1927.
- Next visit after this one
- 9th November 2031At 79.3 lunar distances. Closer than this time.
- Average gap between visits
- 5.0 yearsThe span of the record divided by the number of gaps between approaches.
- Rank by size
- 14 of 42Among every asteroid this site has tracked, biggest first.
- Rank by closeness
- 21 of 42Among every asteroid this site has tracked, using each one's most recent pass, closest first.
- Rank by speed
- 10 of 42Among every asteroid this site has tracked, fastest first.
How reliable are these?
Width, speed, miss distance and orbit come straight from NASA. Mass, energy, volume and the rankings are our own arithmetic on top, and the assumptions are written beside each one. NASA publishes a range for width because nobody has seen most of these rocks up close, so wherever we show one number it uses the biggest estimate and says so.
Will asteroid 2011 UB131 hit Earth? Questions answered
Will asteroid 2011 UB131 hit Earth?
No. 2011 UB131 passes Earth on 13th November 2026 at 98.9 lunar distances (38,051,109 km), which is 98.9 times the distance to the Moon. It is not on NASA's potentially hazardous list. It is not on NASA's Sentry impact-risk watch list.
How big is asteroid 2011 UB131?
NASA estimates it is between 138 m and 309 m wide, which at the top end is about 2.9 football pitches long. Nobody has seen it up close, so the width is an estimate from its brightness.
How fast is asteroid 2011 UB131 travelling?
18.3 km/s relative to Earth at closest approach, about 65,823 km/h (40,900 mph). That is 2.4 times the speed of the International Space Station.
Is 2011 UB131 a potentially hazardous asteroid?
No. NASA gives the label to asteroids whose orbit comes within 0.05 astronomical units of Earth's (about 7.5 million km) and which are bigger than roughly 140 m. 2011 UB131 has an absolute magnitude of 21.4 and its orbit comes within 0.137 AU of Earth's.
When is asteroid 2011 UB131's next close approach?
After this pass, the next one in NASA's record is on 9th November 2031, at 79.3 lunar distances.
Unhelpful facts
- A UK train would take 43.4 years to cross the same gap, plus delays "due to a train being late".
- Flying a gap that size takes it 24.1 days, which is 1,734 twenty-minute naps. Recommended.
- 1,287 basketballs wide. Somebody in the NBA has already asked for the numbers.
- If it did hit, that would release roughly 1,853 megatons of TNT, assuming solid rock. It will not, so enjoy the number.
- In the 24.1 days it takes to fly a gap that size, you could drink 1,734 cups of tea. Most would go cold.
- 25.44% of the way to the Sun. Nobody is cancelling summer.
- About 2.9 football pitches long. Still no better than a mid-table side.
- Light crosses the gap in 126.92 seconds. That is not enough time to say "what was that".
- 869 large pizzas wide. Delivery in thirty minutes or it is free (it will not be free).
- A snail would need 92,357 years to cover the gap. The snail would take the day off.
- At its speed it covers a gap the size of its miss distance in 24.1 days. A group chat would still be picking a restaurant.
- It passes today. Your dog already knows and is not saying anything.