stars can image their own light but not planets cannot why
Answers
planets do not have their own light. so they do not
Planets don't have their own light. So they do not emit light. This phenomena goes back to their formation. When they are formed, they are much much less hotter than stars. In stars, fusion reaction always goes on, and thus energy, as well as light is formed. So, there is light for stars to emit for a long period. To see, how planets are formed, you can visit- How Do Planets Form?. But you can see the Venus, the Mars in the sky, right? They do not have their own light, rather they reflect the light of the sun.
And the answer to your second question is much simpler. Have you ever looked to far away lights in a windy night? You would the twinkling effect in this case as well. It happens for the wind. This phenomena is called- Refraction. If you go outside the earth, you won't see any twinkling effect, as there is no air there. In vacuum, there is nothing, and the Refractive index of all spectrum of light is the same. But after light enters the Atmosphere of Earth, to reach your eyes, it has to come through 9 km(30000 ft) of air. In this medium, light gets refracted. And light does not reach the same point in all the times.