Thursday, July 29, 2010
Two weeks ago I wrote a post here showing the surface area, surface gravity and escape velocity of asteroids of various sizes in order to give some idea of what it would be like to actually explore or live on the surface of one of these, given the fact that the difference between Little Prince-style asteroids where one can break orbit through a simple misstep and 21 Lutetia-sized asteroids where one couldn't break orbit without a velocity similar to a commercial jet is not well known.
One other interesting way to simulate the size of an asteroid is to use this driving simulator here. It's an online simulator that uses Google Maps, and is quite simple in that one does not need to worry about any obstacles - cars, trees, mountains, nothing is a hazard and you can just drive straight through. This makes it a very good tool to show the circumference of an asteroid, i.e. how long it would take to drive from one point all the way around and back again. So let's take a look at the same asteroid sizes given in the chart, and this time instead of giving surface gravity and escape velocity we'll look at their circumference as well as how long it takes to drive around them at various speeds. The simulator goes up to 160 kph, so we'll go with 50 kph (city driving), 100 kph (highway driving) and 160 kph (crazy highway driving or a casual ultralight airplane).
Ceres has been added to the end too even though it's technically not an asteroid.
|Diameter||Circumference||One revolution at 50 kph||100 kph||160 kph|
|314 m||22 seconds||11 seconds||7 seconds|
|500 m||1570 m||112 seconds||56 seconds||35 seconds|
|1 km||3140 m||226 seconds||113 seconds||70 seconds|
|2 km||6.2 km||7.5 minutes||226 seconds||141 seconds|
|3 km||9.4 km||11.2 minutes||5.6 minutes||212 seconds|
|5 km||15.7 km||18.8 minutes||9.4 minutes||5.9 minutes|
|10 km||31.4 km||37.6 minutes||18.8 minutes||11.8 minutes|
|15 km||47.1 km||56.5 minutes||28.2 minutes||17.6 minutes|
|20 km||62.8 km||75.2 minutes||37.6 minutes||23.5 minutes|
|25 km||78.5 km||94 minutes||47 minutes||29.3 minutes|
|30 km||94.2 km||112 minutes||56 minutes||35 minutes|
|35 km||110 km||2.2 hours||66 minutes||41 minutes|
|40 km||126 km||2.5 hours||75 minutes||48 minutes|
|45 km||140 km||2.8 hours||84 minutes||53 minutes|
|50 km||157 km||3.1 hours||94 minutes||47 minutes|
|60 km||190 km||3.8 hours||114 minutes||59 minutes|
|70 km||220 km||4.4 hours||2.2 hours||82 minutes|
|80 km||250 km||5 hours||2.5 hours||94 minutes|
|90 km||282 km||5.6 hours||2.8 hours||107 minutes|
|100 km||314 km||6.3 hours||3.1 hours||118 minutes|
|125 km||392 km||7.8 hours||3.9 hours||146 minutes|
|150 km||470 km||9.4 hours||4.7 hours||2.9 hours|
|175 km||550 km||11 hours||5.5 hours||3.4 hours|
|200 km||628 km||12.6 hours||6.3 hours||3.9 hours|
|250 km||785 km||15.7 hours||7.85 hours||4.9 hours|
|300 km||942 km||18.8 hours||9.4 hours||5.9 hours|
|1660 km||33 hours||16.6 hours||10.4 hours|
|Ceres (950 km)||2984 km||60 hours||30 hours||18.7 hours|
So if someone wants to know for example how large 21 Lutetia is (the asteroid Rosetta flew by just a few weeks ago), tell them to go to the driving simulator, rev it up to 160 kph, and watch the world pass by for 107 minutes. That's one revolution around 21 Lutetia.
The driving simulator also has an odometer so when actually driving you can just keep an eye on that instead of the clock.