<\/p>\n
Astronomers using NASA\u2019s Hubble Space Telescope<\/a> have found evidence that the spinning of a small comet slowed and then reversed its direction of rotation, offering a dramatic example of how volatile activity can affect the spin and physical evolution of small bodies in the solar system. This is the first time researchers have observed evidence of a comet reversing its spin.\u00a0<\/p>\nThe object, comet 41P\/Tuttle-Giacobini-Kres\u00e1k, or 41P for short, likely originated in the Kuiper Belt, and was flung into its current trajectory by Jupiter\u2019s gravity, now visiting the inner solar system every 5.4 years.<\/p>\nAfter its 2017 close passage around the Sun, scientists found that comet 41P experienced a dramatic slowdown in its rotation. Data from NASA\u2019s Neil Gehrels Swift Observatory in May 2017<\/a> showed the object was spinning three times more slowly than it had in March 2017 when it was observed by the Discovery Channel Telescope at Lowell Observatory in Arizona.<\/p>\nA new analysis of follow-up Hubble observations has shown the spin of this comet took an even more unusual turn.<\/p>\nHubble images from December 2017 detected the comet spinning much faster again, with a period of approximately 14 hours, compared to the 46 to 60 hours measured by Swift. The simplest explanation, researchers say, is that the comet continued slowing until it almost stopped, and was then forced to spin in the near-opposite direction by outgassing jets on its surface.<\/p>\nThe science paper<\/a> detailing this finding published Thursday in The Astronomical Journal.<\/p>\n\n\n\n<\/figure>\nThis artist\u2019s concept depicts comet 41P, a tiny Jupiter-family comet, as it approached the Sun and frozen gases began to sublimate and shoot material off into space.<\/div>\nIllustration: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nSmall, temperamental nucleus<\/strong><\/p>\nHubble also constrains the size of the comet\u2019s nucleus, measuring it at around 0.6 miles across (about a kilometer), or about three times the height of the Eiffel Tower.\u00a0<\/p>\nThis is especially small for a comet, making it easy to torque, or twist.<\/p>\nAs a comet approaches the Sun, heat causes frozen ices to sublimate, venting material into space.\u00a0<\/p>\n\u201cJets of gas streaming off the surface can act like small thrusters,\u201d said paper author David Jewitt of the University of California at Los Angeles. \u201cIf those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates.\u201d<\/p>\nThe comet was originally spinning in one direction, but gas jets pushing against that motion gradually slowed it down. Because the jets kept pushing, they ultimately caused the comet to start rotating in the opposite direction.<\/p>\n\u201cIt\u2019s like pushing a merry-go-round,\u201d said Jewitt. \u201cIf it\u2019s turning in one direction, and then you push against that, you can slow it and reverse it.\u201d<\/p>\nEvidence of rapid evolution<\/strong><\/p>\nThe study also shows that the comet\u2019s overall activity has declined significantly since earlier returns. During its 2001 perihelion passage, 41P was unusually active for its size. By 2017, its gas production had decreased by roughly an order of magnitude.<\/p>\nThis change suggests that the comet\u2019s surface may be evolving quickly, possibly as near-surface volatile materials become depleted or covered by insulating dust layers.<\/p>\nMost changes in comet structure occur over centuries or longer. The rapid rotational shifts observed in comet 41P provide a rare opportunity to witness evolutionary processes unfolding on a human timescale.\u00a0<\/p>\nModeling based on the measured torques and mass loss rates suggest that continued rotational changes could eventually lead to structural instability for comet 41P. If a comet spins too rapidly, centrifugal forces can overcome its weak gravity and strength, potentially causing fragmentation or even disintegration<\/a>.<\/p>\n\u201cI expect this nucleus will very quickly self-destruct,\u201d said Jewitt.<\/p>\nYet, comet 41P has likely occupied its present orbit for roughly 1,500 years.\u00a0<\/p>\n\n\nTo view this video please enable JavaScript, and consider upgrading to a web browser that\n\t\t\t\t\tsupports HTML5 video<\/a><\/p><\/video><\/div>\n<\/div>\n\n\nThis artist\u2019s concept depicts comet 41P as it approached the Sun and frozen gases began to sublimate off the comet\u2019s surface. This animation only depicts one jet, but this comet may have multiple streams of material ejecting into space. This jet is pushing against the comet\u2019s spin, then forcing it in the opposite direction. Small fragments of the comet are also shown spewing into space.<\/div>\n<\/div>\n\nAnimation: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/div>\n<\/div>\n<\/div>\nArchival find<\/strong><\/p>\n
The object, comet 41P\/Tuttle-Giacobini-Kres\u00e1k, or 41P for short, likely originated in the Kuiper Belt, and was flung into its current trajectory by Jupiter\u2019s gravity, now visiting the inner solar system every 5.4 years.<\/p>\n
After its 2017 close passage around the Sun, scientists found that comet 41P experienced a dramatic slowdown in its rotation. Data from NASA\u2019s Neil Gehrels Swift Observatory in May 2017<\/a> showed the object was spinning three times more slowly than it had in March 2017 when it was observed by the Discovery Channel Telescope at Lowell Observatory in Arizona.<\/p>\nA new analysis of follow-up Hubble observations has shown the spin of this comet took an even more unusual turn.<\/p>\nHubble images from December 2017 detected the comet spinning much faster again, with a period of approximately 14 hours, compared to the 46 to 60 hours measured by Swift. The simplest explanation, researchers say, is that the comet continued slowing until it almost stopped, and was then forced to spin in the near-opposite direction by outgassing jets on its surface.<\/p>\nThe science paper<\/a> detailing this finding published Thursday in The Astronomical Journal.<\/p>\n\n\n\n<\/figure>\nThis artist\u2019s concept depicts comet 41P, a tiny Jupiter-family comet, as it approached the Sun and frozen gases began to sublimate and shoot material off into space.<\/div>\nIllustration: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nSmall, temperamental nucleus<\/strong><\/p>\nHubble also constrains the size of the comet\u2019s nucleus, measuring it at around 0.6 miles across (about a kilometer), or about three times the height of the Eiffel Tower.\u00a0<\/p>\nThis is especially small for a comet, making it easy to torque, or twist.<\/p>\nAs a comet approaches the Sun, heat causes frozen ices to sublimate, venting material into space.\u00a0<\/p>\n\u201cJets of gas streaming off the surface can act like small thrusters,\u201d said paper author David Jewitt of the University of California at Los Angeles. \u201cIf those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates.\u201d<\/p>\nThe comet was originally spinning in one direction, but gas jets pushing against that motion gradually slowed it down. Because the jets kept pushing, they ultimately caused the comet to start rotating in the opposite direction.<\/p>\n\u201cIt\u2019s like pushing a merry-go-round,\u201d said Jewitt. \u201cIf it\u2019s turning in one direction, and then you push against that, you can slow it and reverse it.\u201d<\/p>\nEvidence of rapid evolution<\/strong><\/p>\nThe study also shows that the comet\u2019s overall activity has declined significantly since earlier returns. During its 2001 perihelion passage, 41P was unusually active for its size. By 2017, its gas production had decreased by roughly an order of magnitude.<\/p>\nThis change suggests that the comet\u2019s surface may be evolving quickly, possibly as near-surface volatile materials become depleted or covered by insulating dust layers.<\/p>\nMost changes in comet structure occur over centuries or longer. The rapid rotational shifts observed in comet 41P provide a rare opportunity to witness evolutionary processes unfolding on a human timescale.\u00a0<\/p>\nModeling based on the measured torques and mass loss rates suggest that continued rotational changes could eventually lead to structural instability for comet 41P. If a comet spins too rapidly, centrifugal forces can overcome its weak gravity and strength, potentially causing fragmentation or even disintegration<\/a>.<\/p>\n\u201cI expect this nucleus will very quickly self-destruct,\u201d said Jewitt.<\/p>\nYet, comet 41P has likely occupied its present orbit for roughly 1,500 years.\u00a0<\/p>\n\n\nTo view this video please enable JavaScript, and consider upgrading to a web browser that\n\t\t\t\t\tsupports HTML5 video<\/a><\/p><\/video><\/div>\n<\/div>\n\n\nThis artist\u2019s concept depicts comet 41P as it approached the Sun and frozen gases began to sublimate off the comet\u2019s surface. This animation only depicts one jet, but this comet may have multiple streams of material ejecting into space. This jet is pushing against the comet\u2019s spin, then forcing it in the opposite direction. Small fragments of the comet are also shown spewing into space.<\/div>\n<\/div>\n\nAnimation: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/div>\n<\/div>\n<\/div>\nArchival find<\/strong><\/p>\n
A new analysis of follow-up Hubble observations has shown the spin of this comet took an even more unusual turn.<\/p>\n
Hubble images from December 2017 detected the comet spinning much faster again, with a period of approximately 14 hours, compared to the 46 to 60 hours measured by Swift. The simplest explanation, researchers say, is that the comet continued slowing until it almost stopped, and was then forced to spin in the near-opposite direction by outgassing jets on its surface.<\/p>\n
The science paper<\/a> detailing this finding published Thursday in The Astronomical Journal.<\/p>\n\n\n\n<\/figure>\nThis artist\u2019s concept depicts comet 41P, a tiny Jupiter-family comet, as it approached the Sun and frozen gases began to sublimate and shoot material off into space.<\/div>\nIllustration: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nSmall, temperamental nucleus<\/strong><\/p>\nHubble also constrains the size of the comet\u2019s nucleus, measuring it at around 0.6 miles across (about a kilometer), or about three times the height of the Eiffel Tower.\u00a0<\/p>\nThis is especially small for a comet, making it easy to torque, or twist.<\/p>\nAs a comet approaches the Sun, heat causes frozen ices to sublimate, venting material into space.\u00a0<\/p>\n\u201cJets of gas streaming off the surface can act like small thrusters,\u201d said paper author David Jewitt of the University of California at Los Angeles. \u201cIf those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates.\u201d<\/p>\nThe comet was originally spinning in one direction, but gas jets pushing against that motion gradually slowed it down. Because the jets kept pushing, they ultimately caused the comet to start rotating in the opposite direction.<\/p>\n\u201cIt\u2019s like pushing a merry-go-round,\u201d said Jewitt. \u201cIf it\u2019s turning in one direction, and then you push against that, you can slow it and reverse it.\u201d<\/p>\nEvidence of rapid evolution<\/strong><\/p>\nThe study also shows that the comet\u2019s overall activity has declined significantly since earlier returns. During its 2001 perihelion passage, 41P was unusually active for its size. By 2017, its gas production had decreased by roughly an order of magnitude.<\/p>\nThis change suggests that the comet\u2019s surface may be evolving quickly, possibly as near-surface volatile materials become depleted or covered by insulating dust layers.<\/p>\nMost changes in comet structure occur over centuries or longer. The rapid rotational shifts observed in comet 41P provide a rare opportunity to witness evolutionary processes unfolding on a human timescale.\u00a0<\/p>\nModeling based on the measured torques and mass loss rates suggest that continued rotational changes could eventually lead to structural instability for comet 41P. If a comet spins too rapidly, centrifugal forces can overcome its weak gravity and strength, potentially causing fragmentation or even disintegration<\/a>.<\/p>\n\u201cI expect this nucleus will very quickly self-destruct,\u201d said Jewitt.<\/p>\nYet, comet 41P has likely occupied its present orbit for roughly 1,500 years.\u00a0<\/p>\n\n\nTo view this video please enable JavaScript, and consider upgrading to a web browser that\n\t\t\t\t\tsupports HTML5 video<\/a><\/p><\/video><\/div>\n<\/div>\n\n\nThis artist\u2019s concept depicts comet 41P as it approached the Sun and frozen gases began to sublimate off the comet\u2019s surface. This animation only depicts one jet, but this comet may have multiple streams of material ejecting into space. This jet is pushing against the comet\u2019s spin, then forcing it in the opposite direction. Small fragments of the comet are also shown spewing into space.<\/div>\n<\/div>\n\nAnimation: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/div>\n<\/div>\n<\/div>\nArchival find<\/strong><\/p>\n
Small, temperamental nucleus<\/strong><\/p>\nHubble also constrains the size of the comet\u2019s nucleus, measuring it at around 0.6 miles across (about a kilometer), or about three times the height of the Eiffel Tower.\u00a0<\/p>\nThis is especially small for a comet, making it easy to torque, or twist.<\/p>\nAs a comet approaches the Sun, heat causes frozen ices to sublimate, venting material into space.\u00a0<\/p>\n\u201cJets of gas streaming off the surface can act like small thrusters,\u201d said paper author David Jewitt of the University of California at Los Angeles. \u201cIf those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates.\u201d<\/p>\nThe comet was originally spinning in one direction, but gas jets pushing against that motion gradually slowed it down. Because the jets kept pushing, they ultimately caused the comet to start rotating in the opposite direction.<\/p>\n\u201cIt\u2019s like pushing a merry-go-round,\u201d said Jewitt. \u201cIf it\u2019s turning in one direction, and then you push against that, you can slow it and reverse it.\u201d<\/p>\nEvidence of rapid evolution<\/strong><\/p>\nThe study also shows that the comet\u2019s overall activity has declined significantly since earlier returns. During its 2001 perihelion passage, 41P was unusually active for its size. By 2017, its gas production had decreased by roughly an order of magnitude.<\/p>\nThis change suggests that the comet\u2019s surface may be evolving quickly, possibly as near-surface volatile materials become depleted or covered by insulating dust layers.<\/p>\nMost changes in comet structure occur over centuries or longer. The rapid rotational shifts observed in comet 41P provide a rare opportunity to witness evolutionary processes unfolding on a human timescale.\u00a0<\/p>\nModeling based on the measured torques and mass loss rates suggest that continued rotational changes could eventually lead to structural instability for comet 41P. If a comet spins too rapidly, centrifugal forces can overcome its weak gravity and strength, potentially causing fragmentation or even disintegration<\/a>.<\/p>\n\u201cI expect this nucleus will very quickly self-destruct,\u201d said Jewitt.<\/p>\nYet, comet 41P has likely occupied its present orbit for roughly 1,500 years.\u00a0<\/p>\n\n\nTo view this video please enable JavaScript, and consider upgrading to a web browser that\n\t\t\t\t\tsupports HTML5 video<\/a><\/p><\/video><\/div>\n<\/div>\n\n\nThis artist\u2019s concept depicts comet 41P as it approached the Sun and frozen gases began to sublimate off the comet\u2019s surface. This animation only depicts one jet, but this comet may have multiple streams of material ejecting into space. This jet is pushing against the comet\u2019s spin, then forcing it in the opposite direction. Small fragments of the comet are also shown spewing into space.<\/div>\n<\/div>\n\nAnimation: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/div>\n<\/div>\n<\/div>\nArchival find<\/strong><\/p>\n
Hubble also constrains the size of the comet\u2019s nucleus, measuring it at around 0.6 miles across (about a kilometer), or about three times the height of the Eiffel Tower.\u00a0<\/p>\n
This is especially small for a comet, making it easy to torque, or twist.<\/p>\n
As a comet approaches the Sun, heat causes frozen ices to sublimate, venting material into space.\u00a0<\/p>\n
\u201cJets of gas streaming off the surface can act like small thrusters,\u201d said paper author David Jewitt of the University of California at Los Angeles. \u201cIf those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates.\u201d<\/p>\n
The comet was originally spinning in one direction, but gas jets pushing against that motion gradually slowed it down. Because the jets kept pushing, they ultimately caused the comet to start rotating in the opposite direction.<\/p>\n
\u201cIt\u2019s like pushing a merry-go-round,\u201d said Jewitt. \u201cIf it\u2019s turning in one direction, and then you push against that, you can slow it and reverse it.\u201d<\/p>\n
Evidence of rapid evolution<\/strong><\/p>\nThe study also shows that the comet\u2019s overall activity has declined significantly since earlier returns. During its 2001 perihelion passage, 41P was unusually active for its size. By 2017, its gas production had decreased by roughly an order of magnitude.<\/p>\nThis change suggests that the comet\u2019s surface may be evolving quickly, possibly as near-surface volatile materials become depleted or covered by insulating dust layers.<\/p>\nMost changes in comet structure occur over centuries or longer. The rapid rotational shifts observed in comet 41P provide a rare opportunity to witness evolutionary processes unfolding on a human timescale.\u00a0<\/p>\nModeling based on the measured torques and mass loss rates suggest that continued rotational changes could eventually lead to structural instability for comet 41P. If a comet spins too rapidly, centrifugal forces can overcome its weak gravity and strength, potentially causing fragmentation or even disintegration<\/a>.<\/p>\n\u201cI expect this nucleus will very quickly self-destruct,\u201d said Jewitt.<\/p>\nYet, comet 41P has likely occupied its present orbit for roughly 1,500 years.\u00a0<\/p>\n\n\nTo view this video please enable JavaScript, and consider upgrading to a web browser that\n\t\t\t\t\tsupports HTML5 video<\/a><\/p><\/video><\/div>\n<\/div>\n\n\nThis artist\u2019s concept depicts comet 41P as it approached the Sun and frozen gases began to sublimate off the comet\u2019s surface. This animation only depicts one jet, but this comet may have multiple streams of material ejecting into space. This jet is pushing against the comet\u2019s spin, then forcing it in the opposite direction. Small fragments of the comet are also shown spewing into space.<\/div>\n<\/div>\n\nAnimation: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/div>\n<\/div>\n<\/div>\nArchival find<\/strong><\/p>\n
The study also shows that the comet\u2019s overall activity has declined significantly since earlier returns. During its 2001 perihelion passage, 41P was unusually active for its size. By 2017, its gas production had decreased by roughly an order of magnitude.<\/p>\n
This change suggests that the comet\u2019s surface may be evolving quickly, possibly as near-surface volatile materials become depleted or covered by insulating dust layers.<\/p>\n
Most changes in comet structure occur over centuries or longer. The rapid rotational shifts observed in comet 41P provide a rare opportunity to witness evolutionary processes unfolding on a human timescale.\u00a0<\/p>\n
Modeling based on the measured torques and mass loss rates suggest that continued rotational changes could eventually lead to structural instability for comet 41P. If a comet spins too rapidly, centrifugal forces can overcome its weak gravity and strength, potentially causing fragmentation or even disintegration<\/a>.<\/p>\n\u201cI expect this nucleus will very quickly self-destruct,\u201d said Jewitt.<\/p>\nYet, comet 41P has likely occupied its present orbit for roughly 1,500 years.\u00a0<\/p>\n\n\nTo view this video please enable JavaScript, and consider upgrading to a web browser that\n\t\t\t\t\tsupports HTML5 video<\/a><\/p><\/video><\/div>\n<\/div>\n\n\nThis artist\u2019s concept depicts comet 41P as it approached the Sun and frozen gases began to sublimate off the comet\u2019s surface. This animation only depicts one jet, but this comet may have multiple streams of material ejecting into space. This jet is pushing against the comet\u2019s spin, then forcing it in the opposite direction. Small fragments of the comet are also shown spewing into space.<\/div>\n<\/div>\n\nAnimation: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/div>\n<\/div>\n<\/div>\nArchival find<\/strong><\/p>\n
\u201cI expect this nucleus will very quickly self-destruct,\u201d said Jewitt.<\/p>\n
Yet, comet 41P has likely occupied its present orbit for roughly 1,500 years.\u00a0<\/p>\n
To view this video please enable JavaScript, and consider upgrading to a web browser that\n\t\t\t\t\tsupports HTML5 video<\/a><\/p><\/video><\/div>\n<\/div>\n\n\nThis artist\u2019s concept depicts comet 41P as it approached the Sun and frozen gases began to sublimate off the comet\u2019s surface. This animation only depicts one jet, but this comet may have multiple streams of material ejecting into space. This jet is pushing against the comet\u2019s spin, then forcing it in the opposite direction. Small fragments of the comet are also shown spewing into space.<\/div>\n<\/div>\n\nAnimation: NASA, ESA, CSA, Ralf Crawford (STScI)<\/div>\n<\/div>\n<\/div>\n<\/div>\nArchival find<\/strong><\/p>\n
Archival find<\/strong><\/p>\n