Are there any "tricks" to know when to use "on", "in" and "into" ? How do I know which of them I should use? I tend to use "on" when it is supposed to be "in" and vice versa.

1 On Monday, NASA's Grail spacecraft crashed into the Moon's shadows.

2 On Monday, NASA's Grail spacecraft crashed on the Moon's surface.

3 On Monday, NASA's Grail spacecraft crashed in the Moon's desert.

Can anybody explain me the use of these prepositions in reference to the examples above?

  • If "bill" is a piece of paper or money, its "on the bill" because you can only see or act on the outside of it.
    – user485
    Feb 14, 2013 at 0:32
  • @user3169 hmm, this same rule applies from example to "in the internet" or "on the internet"
    – dreamcrash
    Feb 14, 2013 at 0:34
  • I don't know if the internet has such a description, probably you would say "using the internet" as its actually a service. But you can say "on the computer", "on the phone" or "on the sidewalk" as these are physical objects.
    – user485
    Feb 14, 2013 at 0:40
  • @dreamcrash: Normally one would say "ELL is a website that is on the Internet", and "I read that on the Internet last week". That being said, there is a huge amount of deliberate bad grammar and slang in use on the Internet. So you might see lolcats saying "I'm in ur Internetz, checkin ur emails", but in normal English you should use "on the Internet" rather than "in the Internet".
    – Matt
    Feb 14, 2013 at 0:42
  • @Matt & user3169 Thanks for the explanations. In some case it looks like there is no specific rule, but more of "usage".
    – dreamcrash
    Feb 14, 2013 at 0:54

2 Answers 2


The three uses in your example are quite different:

  • into may refer changing a state, a solid piece into particles: crashed into pieces;
  • into may also refer a direction of physical movement: crashed into a surface;
  • on refers an accident happened on a certain location: crashed on the Moon (meaning, not in space);
  • in also refers location, but connote a more specific location: crashed in the Copernicus crater;
  • in may also refer that an accident happened inside the body of Moon (underground), but that's not the case here;

However, it is correct that in, on, and into have too many meanings to describe a simple rule of thumb.


Regarding #2, "on" is OK, "onto" is also OK, both refer to the surface of the moon.
Regarding #3, its OK.
Regarding #1, it does not make sense since you can't crash into a shadow. But you could say "On Monday, NASA's Grail spacecraft crashed into the Moon's ocean." If it had one, anyway.
It could "cross into the moon's shadow" though.

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