Will it be possible to fry eggs in Sahara desert by just keeping them under the sun? If so, then will the radiated eggs be any different? Or will we have to use the solar cooking concept to some extent? What is the minimum Intensity required and the temperature to achieve this? (With and without solar cooker)
There are many models of solar cookers relying on various phenomena.
Two that come to mind are :
You could also use a lense to concentrate radiation, but there is probably loss in the lens, and it is heavy as soon as it is large.
It should often be usable in other places than desert as long as the sun shines, and makes for more ecological barbecues.
If you meant to cook without any equipment at all, you might try to bury the food in very hot sand, preferably dark. I am not sure whether it works or how fast. I read you can cook an egg at 55 Celsius, which is very hot on the feet, but still a temperature found in desertic grounds (sometimes even in cities).
In principle, yes, if you can prevent the egg (and the surface it is on) from being cooled too much by the air. The temperature needed to cook the egg is around 100c or less, while the temperature of the sun's surface is around 5000c. All a solar cooker does is make the sun look larger, from the egg's perspective.