Twitter Images Not Showing

Hey guys, what size do you use for your twitter images. I use 500x500 and I find the picture don't look right. Any size advice for these picture we post on twitter. Thanks

have a look here
http://blog.hubspot.com/marketing/ultimate-guide-social-media-image-dimensions-infographic
all the info that you need

Hi,
You cannot have the image size in the ratio 1:1. It has to be in the ratio 2:!. The image size must be minimum 440 x 220 px. If you want the photo displayed io be the same as the original, it cannot exceed the following measurements: 1024 x 512 px (2:1 aspect).

This is why the image is not looking right.