A Thousand Coins

I've laid out 1000 coins on a table, with exactly 20 coins heads up and the remaining 980 tails up. You can't see the coins because you've been blindfolded, but I ask you to split the coins into exactly two groups such that each group has an equal number of heads up coins. You can't know if a coin is heads or tails by touching it, but you can flip as many coins as you want. Is this possible? If so, what's your strategy?

Source: The green book