Stellar aberration of light

What you are seeing: star positions as they appear to an observer moving at velocity $\beta c$ along the $+x$ axis, compared to their rest-frame positions. The Lorentz aberration formula $\cos\theta_\text{obs} = (\cos\theta_\text{rest} + \beta) / (1 + \beta \cos\theta_\text{rest})$ pulls every star toward the forward direction (relativistic beaming in geometry). For Earth's annual orbital aberration ($\beta \approx 10^{-4}$), the maximum shift is the classical constant of aberration $\approx 20.5"$.

Rest-frame stars are drawn at uniform angles around the observer (cyan dots); their observed positions cluster forward (orange dots). Connecting lines show the shift; the maximum-shift line is highlighted in accent. As $\beta \to 1$ the entire visible sphere concentrates into a forward cone.