Yes and all light casts shadows IR included. Take a look at any video of a plane casting a shadow onto clouds. eg. https://youtu.be/Vr_kYmUaykw?t=7

Notice the similarities? The halo and the matching of the recording planes movements which are explicitly mentioned in this.

Yes but the IR locked onto a higher temperature source, not cooler. My understanding is that a shadow would be cooler.

Other remaining factors include that:

- Primary radars on both fighters in the initial pass were being jammed

- Passive radars on the Nimitz were what directed the planes to this spot initially

- It was approximately 9:30-10 PST, so any shadow from <40k feet would be coming from restricted airspace

- Multiple visual contacts from multiple angles, including from slightly below/ to the side

This one is pretty difficult to explain in conventional terms, unless you think it's all a hoax. Pretty fascinating stuff, huh?