Category: Astronomy

  • For the dinosaurs!

    John F. Lindner

    The dinosaurs didn’t have a space program, but we do. I just watched live the first kinetic-impact asteroid-redirection test as NASA’s Double Asteroid Redirection Test spacecraft collided with the asteroid-moon Dimorphos of the asteroid Didymos. Below is the last image DART transmitted, truncated by the impact itself! The goal is to measurably change the speed…

  • Great Plains Solstice Twilight

    John F. Lindner

    Last month I drove across the United States, coast-to-coast back-and-and forth diagonally, 8000 miles through 18 states, as in the animation below. Amazing was driving through the Great Plains of the North American flatland with uninterrupted 360° horizons as the sun slowly set and civil, nautical, and astronomical twilight seemed impossibly long. The explanation was…

  • Signature Spikes

    John F. Lindner

    Nearly a quarter century in the making, I was tremendously excited and relieved last week by the release of the first images from the James Webb Space Telescope. I remember the trials, tribulations, and triumph of the Hubble Space Telescope and am now confident that Webb’s gallery of images and spectra will meet or exceed Hubble’s…

  • Alien Suns Reversing in Exoplanet Skies

    John F. Lindner

    Not only can suns stand still in the sky, from some exoplanets their motion can apparently reverse! Wooster physics-math double majors Xinchen (Ariel) Xie ’21 and Hwan (Michelle) Bae ’19 and I just published an article elucidating these apparent solar reversals. Michelle and I began studying the architecture of daylighting terrestrial buildings for energy efficiency as part…

  • Black Hole Above the Fold

    John F. Lindner

    When grocery shopping, I normally just glance at the newspapers in the newsstand. However, this morning, I was excited to see “above the fold” of the Wall Street Journal a large reproduction of the first image of the supermassive black hole Sagittarius A* at the center of our Milky Way galaxy! The Event Horizon Telescope team…

  • Slide Rule Examples

    John F. Lindner

    Slide rules were widely used in engineering, science, and mathematics until the early 1970s, including during the Gemini and Apollo space programs. Although rendered largely obsolete by the advent of inexpensive electronic calculators, their descendants continue to have specialized applications, such as backup flight computers. Buzz Aldrin and a floating slide rule during Gemini 12 on…

  • Diffraction Limited

    John F. Lindner

    Yesterday, Webb optical telescope element manager Lee Feinberg said “We made the right telescope” while reporting that its focus has reached the  diffraction limit of 0.7 arcseconds at the infrared wavelength of 2 microns. (For comparison, from Earth, Luna subtends 31 arcminutes, which is about 1/2°.) Unlike the Hubble space telescope, whose primary mirror was…

  • Halo Orbit

    John F. Lindner

    The Webb telescope has fully deployed and arrived at its halo orbit about the second Earth-Sun Lagrange point. But how can it orbit an empty point in space? In the accompanying animated sequence of inertial space diagrams, a star (red) and planet (cyan) orbit their common center of mass (cross). The inward force to pull…

  • Astronomy Christmas Gift

    John F. Lindner

    I awoke early this Christmas morning to watch the successful launch of the James Webb Space Telescope. I remember the genesis of the telescope a quarter of a century ago when it was called the Next Generation Space Telescope. (The telescope’s name is controversial, and I would have preferred an astronomer’s name.) Its development has…

  • Part Science, Part Art, Part Luck

    John F. Lindner

    Launched just last month, Lucy will be the first spacecraft to visit Jupiter’s trojan asteroids, rocky swarms that orbit about 60 degrees ahead and behind Jupiter in its orbit. Hal Levison, Lucy’s Principal Investigator, has described Lucy’s complicated trajectory, which includes an Earth gravity-assist and visits to both trojan swarms, as “part science, part art, and part luck”.…

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