If it doesn’t twinkle, it’s a planet. Saw two the other morning. Venus is the brightest. Mars is actually red. I also got to see a shooting star Sunday am and I am in the philly suburbs so it was a bright one.
Twinkling, or to use the astronomical term, scintillation, is a product of the atmosphere, not the observed body. With clear, cold air scintillation is minimal, but given an atmosphere that is thermally unstable, all objects twinkle. Planets however, are actually tiny discs rather than a point light source, so in marginally unstable air, their scintillation averaged out over a larger area, so they appear to less twinkly.