Planet Science CSI

Our fingerprints are unique. Not even identical twins have fingerprints that are the same. We leave fingerprints on everything we touch. Fingerprints can help detectives solve a crime.

There are three main types of fingerprints - whorls, loops and arches.

Whorl (c) NIST Database

Arch (c) NIST database

Loop (c) NIST database

Can you be a Planet Science detective?

What you need

• Glass
• Pencil
• Paper
• Sellotape
• White card
• Pen
• Talcum powder
• Small paint brush
• Black card

Wipe a glass down. Leave it in the room and ask someone in your family to pick it up - make sure you don't know who touches it! Don't let anyone else touch it afterwards. Leave this for a few hours.

Take your family's fingerprints. The easiest way to do this is to rub a pencil over a small piece of paper. Press your family's fingers onto the pencil. Put a piece of sellotape gently over the finger and then stick it on a piece of white card. You should be able to see the fingerprints clearly. Repeat if you can't. Make sure you label the piece of card so you know whose fingerprint it is!

To dust for fingerprints, sprinkle talcum powder over the glass. Use a small paint brush to gently wipe off excess powder. Can you see any fingerprints? Put sellotape lightly over the fingerprint and peel it off. Stick the sellotape onto a piece of black card. Compare the fingerprints on the glass to your family's fingerprints. Can you identify who touched the glass?