{"id":10584,"date":"2024-04-02T18:03:41","date_gmt":"2024-04-02T22:03:41","guid":{"rendered":"https:\/\/zobi.alcowep.com\/bourtagshdrevxnls658739\/that-starry-night-sky-its-full-of-eclipses\/"},"modified":"2024-04-02T18:03:41","modified_gmt":"2024-04-02T22:03:41","slug":"that-starry-night-sky-its-full-of-eclipses","status":"publish","type":"post","link":"https:\/\/zobi.alcowep.com\/bourtagshdrevxnls658739\/that-starry-night-sky-its-full-of-eclipses\/","title":{"rendered":"That Starry Night Sky? It\u2019s Full of Eclipses"},"content":{"rendered":"

That Starry Night Sky? It\u2019s Full of Eclipses<\/h2>\n

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5 min read<\/p>\n

That Starry Night Sky? It\u2019s Full of Eclipses<\/h1>\n<\/div>\n<\/div>\n<\/div>\n
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\"Artist's<\/figure>
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An artist\u2019s concept shows the TRAPPIST-1 planets as they might be seen from Earth using an extremely powerful \u2013 and fictional \u2013 telescope. <\/div>\n
NASA\/JPL-Caltech<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

Our star, the Sun, on occasion joins forces with the Moon to offer us Earthlings a spectacular solar eclipse \u2013 like the one that will be visible to parts of the United States, Mexico, and Canada on April 8.<\/p>\n

But out there, among the other stars, how often can we see similar eclipses? The answer depends on your point of view. Literally.<\/p>\n

On Earth, a total solar eclipse occurs when the Moon blocks the Sun\u2019s disk as seen from part of Earth\u2019s surface. In this case, the \u201cpath of totality\u201d will be a strip cutting across the country, from Texas to Maine.<\/p>\n

We also can see \u201ceclipses\u201d involving Mercury and Venus, the two planets in our solar system that orbit the Sun more closely than Earth, as they pass between our telescopes and the Sun (though only by using telescopes with protective filters to avoid eye damage). In these rare events, the planets are tiny dots crossing the Sun\u2019s much larger disk.<\/p>\n

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A composite of images of the Venus transit taken by NASA\u2019s Solar Dynamics Observatory on June 5, 2012. The image shows a timelapse of Venus\u2019 path across the Sun.<\/div>\n
NASA\/Goddard\/SDO<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

And astronomers can, in a sense, \u201csee\u201d eclipses among other systems of planets orbiting their parent stars. In this case, the eclipse is a tiny drop in starlight as a planet, from our point of view, crosses the face of its star. That crossing, called a transit, can register on sensitive light sensors attached to telescopes on Earth and those in space, such as NASA\u2019s Hubble Space Telescope, James Webb Space Telescope, or TESS (the Transiting Exoplanet Survey Satellite). It\u2019s how the bulk of the more than 5,500 confirmed exoplanets \u2013 planets around other stars \u2013 have been detected so far, although other methods also are used to detect exoplanets.<\/p>\n

\u201cA solar eclipse is a huge transit,\u201d said Allison Youngblood, the deputy project scientist for TESS at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland.<\/p>\n

And both types of \u201ctransits\u201d \u2013 whether they involve solar eclipses or exoplanets \u2013 can yield world-changing science. Solar eclipse observations in 1919 helped prove Einstein\u2019s theory of general relativity, when the bending of a star\u2019s light by the Sun\u2019s gravity caused the star\u2019s apparent position to shift \u2013 showing that gravity causes space and time to curve around it.<\/p>\n

Exoplanet transits also provide far more than just detections of distant planets, Youngblood said.<\/p>\n

\u201cThe planet passes in front of the star, and blocks a certain amount of the star\u2019s light,\u201d she said. \u201cThe dip [in starlight] tells us about the size of the planet. It gives us a measurement of the radius of the planet.\u201d<\/p>\n

Careful measurements of multiple transits also can reveal how long a year is on an exoplanet, and provide insights into its formation and history. Careful measurements of multiple transits also can provide insights into exoplanet formation and history.<\/p>\n

And the starlight shining through the exoplanet\u2019s atmosphere during its transit, if measured using an instrument called a spectrograph, can reveal deeper characteristics of the planet itself. The light is split into a rainbow-like spectrum, and slices missing from the spectrum can indicate gases in the planet\u2019s atmosphere that absorbed that \u201ccolor\u201d \u2013 or wavelength.<\/p>\n

\u201cMeasuring the planet at many wavelengths tells us what chemicals and what molecules are in that planet\u2019s atmosphere,\u201d Youngblood said.<\/p>\n

Eclipses are such a handy way to capture information about distant worlds that scientists have learned how to create their own. Instead of waiting for eclipses to occur in nature, they can engineer them right inside their telescopes. Instruments called coronagraphs, first used on Earth to study the Sun\u2019s outer atmosphere (the corona), are now carried aboard several space telescopes. And when NASA\u2019s next flagship space telescope, the Nancy Grace Roman Space Telescope, launches by May 2027, it will demonstrate new coronagraph technologies that have never been flown in space before. Coronagraphs use a system of masks and filters to block the light from a central star, revealing the far fainter light of planets in orbit around it.<\/p>\n

Of course, that isn\u2019t quite as easy as it sounds. Whether searching for transits, or for direct images of exoplanets using a coronagraph, astronomers must contend with the overwhelming light from stars \u2013 an immense technological challenge.<\/p>\n

\u201cAn Earth-like transit in front of stars is equivalent to a mosquito walking in front of a headlight,\u201d said David Ciardi, chief scientist at the NASA Exoplanet Science Institute at Caltech. \u201cThat\u2019s how little light is blocked.\u201d<\/p>\n

We don\u2019t have this problem when viewing solar eclipses \u2013 \u201cour very first coronagraphs,\u201d Ciardi says. By pure happenstance, the Moon covers the Sun completely during an eclipse.<\/p>\n

\u201cA solar eclipse is like a human walking in front of a headlight,\u201d he said.<\/p>\n

We would have no such luck on other planets in our solar system.<\/p>\n

Mars\u2019 oddly shaped moons are too small to fully block the Sun during their transits; and while eclipses might be spectacular among the outer planets \u2013 for instance, Jupiter and its many moons \u2013 they wouldn\u2019t match the total coverage of a solar eclipse.<\/p>\n

We happen to be living at a fortunate time for eclipse viewing. Billions of years ago, the Moon was far closer to Earth, and would have appeared to dwarf the Sun during an eclipse. And in about 700 million years, the Moon will be so much farther away that it will no longer be able to make total solar eclipses.<\/p>\n

\u201cA solar eclipse is the pinnacle of being lucky,\u201d Tripathi said. \u201cThe Moon\u2019s size and distance allow it to completely block out the Sun\u2019s light. We\u2019re at this perfect time and place in the universe to be able to witness such a perfect phenomenon.\u201d<\/p>\n

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