At a glance
- Width
- 5 to 11 m
- about 40 bananas
- Speed
- 9.08 km/s
- 32,685 km/h · 20,309 mph
- Misses us by
- 67.2 lunar
- 25,835,106 km · 16,053,185 miles
- First spotted by us
- 13th November 2026
- 1 page view
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
- ATEAten: crosses Earth's orbit while spending most of its time inside it, between us and the Sun.
- Year length
- 0.80 Earth years (294 days)One lap of the Sun. Your commute is shorter, and so is your patience.
- Eccentricity
- 0.157How squashed the orbit is. 0 is a perfect circle, 1 is "leaving". This one is nearly circular and well behaved.
- Tilt
- 4.7°The angle of its orbit against the flat plane the planets share. Basically flat, so it shares our neighbourhood.
- Closest to the Sun
- 0.73 AU109 million km. One AU is the distance from Earth to the Sun.
- Furthest from the Sun
- 1.00 AU150 million km. Never leaves the inner solar system.
- Closest orbit-to-orbit gap
- 0.003 AUIf you only compare the two orbits, not where the planets are, they come within 1 lunar distances. The rock is rarely there at the same time as us, which is the entire reason we are still here.
- Observations used
- 70NASA has measured this one 70 times. It has been stalked thoroughly.
- Watched for
- 16 days2018-11-27 to 2018-12-13. Not long, so the orbit is still being refined and the rock is still a bit of a stranger.
- Orbit uncertainty
- 5 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.
On NASA's Sentry watch list, which means "monitored for any future chance of impact", not "doomed". Every watch-list rock so far has been cleared or filed under "very unlikely".
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 |
|---|---|---|
| 17th January 2015 | 33.4 LD · 12,828,275 km | 5.5 km/s |
| 25th November 2018 | 1.2 LD · 453,144 km | 4.2 km/s |
| 16th November 2022 | 26.8 LD · 10,312,984 km | 5.9 km/s |
| 19th March 2023 | 75.3 LD · 28,940,892 km | 3.7 km/s |
| 17th November 2026 (this one) | 67.2 LD · 25,835,106 km | 9.1 km/s |
| 12th April 2027 | 89.6 LD · 34,466,158 km | 5.9 km/s |
| 17th November 2030 | 80.1 LD · 30,821,894 km | 10.1 km/s |
| 19th April 2031 | 93.4 LD · 35,925,583 km | 6.4 km/s |
| 18th November 2034 | 96.6 LD · 37,150,397 km | 11.5 km/s |
| 20th November 2038 | 126.8 LD · 48,770,328 km | 14.0 km/s |
By the numbers
- Estimated mass
- 204 tonnes to 2,282 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
- 0 Olympic poolsSphere volume at the middle width estimate, divided by 2,500 cubic metres per Olympic pool.
- Impact energy, if it hit
- 2.0 kilotons to 22 kilotonsHalf 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
- 0.8 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
- 0.30 timesDivided by Earth's own orbital speed of 29.78 km/s around the Sun.
- Time to cross the UK
- 106.8 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
- 32.9 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
- 86.2 secondsMiss distance divided by the speed of light.
- Width from brightness alone
- 5 to 11 mAstronomers estimate size from how bright an asteroid is (H 28.6) 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
- 0.116 days of observation divided by its 294-day year.
- Known close approaches, 1900 to 2200
- 300 inside the Moon's orbit and 1 within ten lunar distances.
- Closest pass in that period
- 1.18 lunar distancesOn 25th November 2018.
- Next visit after this one
- 12th April 2027At 89.6 lunar distances. No closer than this time.
- Average gap between visits
- 2.3 yearsThe span of the record divided by the number of gaps between approaches.
- Rank by size
- 41 of 42Among every asteroid this site has tracked, biggest first.
- Rank by closeness
- 18 of 42Among every asteroid this site has tracked, using each one's most recent pass, closest first.
- Rank by speed
- 35 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 2018 WH1 hit Earth? Questions answered
Will asteroid 2018 WH1 hit Earth?
No. 2018 WH1 passes Earth on 17th November 2026 at 67.2 lunar distances (25,835,106 km), which is 67.2 times the distance to the Moon. It is not on NASA's potentially hazardous list. It is on NASA's Sentry watch list, which means "monitored for any future chance of impact", not "expected to hit".
How big is asteroid 2018 WH1?
NASA estimates it is between 5 m and 11 m wide, which at the top end is about 0.1 football pitches long. Nobody has seen it up close, so the width is an estimate from its brightness.
How fast is asteroid 2018 WH1 travelling?
9.1 km/s relative to Earth at closest approach, about 32,685 km/h (20,309 mph). That is 1.2 times the speed of the International Space Station.
Is 2018 WH1 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. 2018 WH1 has an absolute magnitude of 28.6 and its orbit comes within 0.003 AU of Earth's.
When is asteroid 2018 WH1's next close approach?
After this pass, the next one in NASA's record is on 17th November 2026, at 67.2 lunar distances.
Unhelpful facts
- It could overtake 36 commercial jets, and it would not even signal.
- Absolute magnitude of 28.6. Lower means brighter, so the biggest numbers belong to the smallest rocks. Astronomers did that on purpose.
- It passes in 4 days, which is 28 dog days. Your dog is already nervous, mostly about the post.
- Line up 1 elephants to match its width. The elephants would like to be consulted first.
- 17.27% of the way to the Sun. Nobody is cancelling summer.
- Light crosses the gap in 86.18 seconds. That is not enough time to say "what was that".
- If this one did hit Earth, your next meeting would be cancelled. Look on the bright side.
- At this speed it covers the distance to the Moon in 11.8 hours. Your train replacement bus takes longer.
- It is moving 93 times faster than a sports car, and has never once paid a congestion charge.
- A jet would have to circle Earth 644 times to cover the gap. Baggage still lost.
- As fast as 730 Usain Bolts at top speed, none of whom have been told.
- A snail would need 62,706 years to cover the gap. The snail would take the day off.