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Galaxy sizes and their evolution over cosmic time have been studied fordecades and serve as key tests of galaxy formation models. However, at$z\gtrsim1$ these studies have been limited by a lack of deep, high-resolutionrest-frame infrared imaging that accurately traces galaxy stellar massdistributions. Here, we leverage the new capabilities of the James Webb SpaceTelescope to measure the 4.4$\mu$m sizes of ${\sim}1000$ galaxies with$\log{\rm{M}_*/\rm{M}_\odot}\ge9$ and $1.0\le z \le 2.5$ from public CEERSimaging in the EGS deep field. We compare the sizes of galaxies measured fromNIRCam imaging at 4.4$\mu$m ($\lambda_{\mathrm{rest}}\sim1.6\mu $m) with sizesmeasured at $1.5\mu$m ($\lambda_{\mathrm{rest}}\sim5500$A). We find that, onaverage, galaxy half-light radii are $\sim8$% smaller at 4.4$\mu$m than1.5$\mu$m in this sample. This size difference is markedly stronger at higherstellar masses and redder rest-frame $V-J$ colors: galaxies with ${\rm M}_*\sim 10^{11}\,{\rm M}_\odot$ have 4.4$\mu$m sizes that are $\sim 25$% smallerthan their 1.5$\mu$m sizes. Our results indicate that galaxy mass profiles aresignificantly more compact than their rest-frame optical light profiles atcosmic noon, and demonstrate that spatial variations in age and attenuation areimportant, particularly for massive galaxies. The trend that we find hereimpacts our understanding of the size growth and evolution of galaxies, andsuggests that previous studies based on rest-frame optical light may not havecaptured the mass-weighted structural evolution of galaxies. This paperrepresents a first step towards a new understanding of the morphologies ofearly massive galaxies enabled by JWST's infrared window into the distantuniverse.

Rest-frame near-infrared sizes of galaxies at cosmic noon: objects in JWST's mirror are smaller than they appeared