“The sign cosmologists want to read is a cosmic speed limit sign that tells us how fast the universe is expanding - a number called the Hubble constant. “Did you ever struggle to see a sign that was at the edge of your vision? What does it say? What does it mean? Even with the most powerful telescopes, the ‘signs’ astronomers want to read appear so small that we struggle too. The circle is red in the Webb image and white in the Hubble image. In both images a central black spot is circled. The black spots in the Webb image are smaller, more distinct, and more numerous than in the Hubble image. Both images show black to gray mottling, but the texture in the Webb image is finer. The top image is labeled “HST WFC3-IR.” The bottom image is labeled “JWST NIRCAM.” Both images have distinct pixilation, but the pixels in the Hubble image at the top are noticeably larger than those in the Webb image at the bottom. Both are square and they are the same size. On the right side of the graphic are two grayscale images stacked vertically.

The red sphere is labeled “Cepheid.” Image Details This box is also filled with blue-green spheres and one red sphere, but the spheres are significantly smaller and there is less overlap between spheres. The box has the same dimensions, orientation, and depth label as the box above. The bottom diagram is almost the same, with an illustration of the Webb Space Telescope at the left, pointing toward another large transparent box at the right. The box contains numerous blue-green spheres of different sizes, with a red sphere near the middle.

The long edge of the base is labeled “depth” with an arrow pointing from front face the toward the back. The box is oriented such that three sides are visible. The top diagram includes an illustration of the Hubble Space Telescope on the left, pointing toward a large transparent box at the right. In the middle if the graphic is a set of two vertically stacked diagrams illustrating zoomed-in views of the region of the galaxy outlined with the white box. On the right side of the image, a small portion of one of the spiral arms is outlined with a white transparent box. Scattered along and between the arms are a number of relatively large, glowing-red spots. The arms consist of tiny blue-white points of light, with streams and filaments of reddish-brown, and small pockets of pinkish glow. On the left side of the graphic, a colorful telescope image of part of a spiral galaxy is labeled “NGC 5584 (Webb NIRCam + Hubble WFC3).” The galaxy has four arms winding out from a bright tannish-white bar-shaped region in the center. Graphic titled “Uncrowding Cepheids in the Near-Infrared” consists of three parts: a Hubble and Webb image of spiral galaxy NGC 5584 a diagram comparing the resolution of the Webb data to that of the Hubble data and a comparison of a Webb NIRCam image detail to the Hubble WFC3-IR image detail of the same region.

Black and white spiral background