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Rainbows are spectacular things. But I imagine why we can't reach to the ends of rainbows. Do rainbows have no ends ? If so, why can't we reach at them? If you go closer,they will go further. Why?

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    $\begingroup$ Rainbows are circles so they have no ends. They look semicircular because we can usually only see part of them. $\endgroup$
    – John Rennie
    Commented Oct 19, 2014 at 18:44
  • $\begingroup$ Worse, still, rainbows are wedges. The prismatic refraction could be coming from ten feet from your eyes or from ten miles away. You can try this at home by spraying water from a garden hose trough a nozzle. It makes for great rainbows. $\endgroup$
    – CuriousOne
    Commented Oct 19, 2014 at 18:47
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    $\begingroup$ And even worse still, when you move the rainbow moves, and every one sees a different rainbow. $\endgroup$
    – DJohnM
    Commented Oct 20, 2014 at 1:58

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Why can't we reach the ends of rainbow?

The WIkipedia article you linked to contains the explanation

The rainbow is not located at a specific distance, but comes from an optical illusion caused by any water droplets viewed from a certain angle relative to a light source. Thus, a rainbow is not an object and cannot be physically approached. Indeed, it is impossible for an observer to see a rainbow from water droplets at any angle other than the customary one of 42 degrees from the direction opposite the light source.

If you go closer,they will go further. Why?

The primary rainbow is refracted at an angle of 42 degrees. If you are at an angle of say 52 degrees from some droplets you won't see any light refracted by those particular droplets.

enter image description here

As you walk 1 meter towards the droplets that are refracting the rainbow you initially see, you move outside the the "beam" from those specific droplets and move into the "beam" refracted by droplets 1 m further back.

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You can reach the end of a rainbow, if you make one using a hose pipe on a sunny day. It is possible to locate the ends to within a few centimeter.

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