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At a glance
- Width
- 92 to 206 m
- about 745 bananas
- Speed
- 23.02 km/s
- 82,878 km/h · 51,498 mph
- Misses us by
- 54.3 lunar
- 20,892,346 km · 12,981,898 miles
- First spotted by us
- 14th November 2026
- 0 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
- AMOAmor: approaches Earth's orbit without ever crossing it. Looks threatening. Isn't.
- Year length
- 1.80 Earth years (656 days)One lap of the Sun. Your commute is shorter, and so is your patience.
- Eccentricity
- 0.281How squashed the orbit is. 0 is a perfect circle, 1 is "leaving". Noticeably oval. Mildly dramatic.
- Tilt
- 42.0°The angle of its orbit against the flat plane the planets share. Properly tilted. It mostly visits from above or below.
- Closest to the Sun
- 1.06 AU159 million km. One AU is the distance from Earth to the Sun.
- Furthest from the Sun
- 1.89 AU283 million km. Out past Mars.
- Closest orbit-to-orbit gap
- 0.097 AUIf you only compare the two orbits, not where the planets are, they come within 38 lunar distances. The rock is rarely there at the same time as us, which is the entire reason we are still here.
- Observations used
- 72NASA has measured this one 72 times. It has been stalked thoroughly.
- Watched for
- 45 days2017-11-27 to 2018-01-11. Not long, so the orbit is still being refined and the rock is still a bit of a stranger.
- Orbit uncertainty
- 6 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 |
|---|---|---|
| 13th November 1974 | 148.5 LD · 57,097,406 km | 25.7 km/s |
| 4th December 1999 | 151.5 LD · 58,269,453 km | 23.3 km/s |
| 29th November 2008 | 91.1 LD · 35,048,426 km | 22.4 km/s |
| 25th November 2017 | 42.8 LD · 16,470,847 km | 22.4 km/s |
| 21st November 2026 (this one) | 54.3 LD · 20,892,346 km | 23.0 km/s |
| 17th November 2035 | 109.1 LD · 41,967,556 km | 24.5 km/s |
| 11th November 2044 | 170.6 LD · 65,609,329 km | 26.6 km/s |
| 6th December 2060 | 193.4 LD · 74,365,782 km | 24.2 km/s |
| 2nd December 2069 | 130.5 LD · 50,198,881 km | 22.9 km/s |
| 28th November 2078 | 72.0 LD · 27,702,066 km | 22.3 km/s |
By the numbers
- Estimated mass
- 1.2 million tonnes to 13.7 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
- 695 Olympic poolsSphere volume at the middle width estimate, divided by 2,500 cubic metres per Olympic pool.
- Impact energy, if it hit
- 78 megatons to 871 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
- 2.1 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
- 0.77 timesDivided by Earth's own orbital speed of 29.78 km/s around the Sun.
- Time to cross the UK
- 42.1 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
- 10.5 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
- 69.7 secondsMiss distance divided by the speed of light.
- Width from brightness alone
- 92 to 206 mAstronomers estimate size from how bright an asteroid is (H 22.3) 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
- 0.145 days of observation divided by its 656-day year.
- Known close approaches, 1900 to 2200
- 100 inside the Moon's orbit and 0 within ten lunar distances.
- Closest pass in that period
- 42.83 lunar distancesOn 25th November 2017.
- Next visit after this one
- 17th November 2035At 109.1 lunar distances. No closer than this time.
- Average gap between visits
- 11.6 yearsThe span of the record divided by the number of gaps between approaches.
- Rank by size
- 19 of 45Among every asteroid this site has tracked, biggest first.
- Rank by closeness
- 14 of 45Among every asteroid this site has tracked, using each one's most recent pass, closest first.
- Rank by speed
- 3 of 45Among 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 2017 WR28 hit Earth? Questions answered
Will asteroid 2017 WR28 hit Earth?
No. 2017 WR28 passes Earth on 21st November 2026 at 54.3 lunar distances (20,892,346 km), which is 54.3 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 2017 WR28?
NASA estimates it is between 92 m and 206 m wide, which at the top end is about 2.0 football pitches long. Nobody has seen it up close, so the width is an estimate from its brightness.
How fast is asteroid 2017 WR28 travelling?
23.0 km/s relative to Earth at closest approach, about 82,878 km/h (51,498 mph). That is 3.0 times the speed of the International Space Station.
Is 2017 WR28 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. 2017 WR28 has an absolute magnitude of 22.3 and its orbit comes within 0.097 AU of Earth's.
When is asteroid 2017 WR28's next close approach?
After this pass, the next one in NASA's record is on 21st November 2026, at 54.3 lunar distances.
Unhelpful facts
- If it did hit, that would release roughly 871 megatons of TNT, assuming solid rock. It will not, so enjoy the number.
- Roughly 317 car tyres wide. Check the tread before you worry about the rock.
- About 588 wheels of Gouda across. A brave scientist would call that a dairy event.
- Light crosses the gap in 69.69 seconds. That is not enough time to say "what was that".
- That is 1,716 times the speed limit on a 30 zone. Nobody has fined it yet.
- Line up 34 elephants to match its width. The elephants would like to be consulted first.
- It is moving 236 times faster than a sports car, and has never once paid a congestion charge.
- 13.97% of the way to the Sun. Nobody is cancelling summer.
- It could overtake 92 commercial jets, and it would not even signal.
- In the 10.5 days it takes to fly a gap that size, you could drink 756 cups of tea. Most would go cold.
- About 2.0 football pitches long. Still no better than a mid-table side.
- If this one did hit Earth, your next meeting would be cancelled. Look on the bright side.