At the center of our solar system, the Sun influences every planet\u00a0that\u00a0orbits\u00a0it.\u00a0In two recent NASA-funded studies, scientists uncovered\u00a0how\u00a0ancient events in the Sun\u2019s history may have helped create Earth\u2019s unique climate and driven previously unexplained climatic shifts.\u00a0\u00a0<\/p>\n
In new research, scientists at NASA\u2019s\u00a0SHIELD<\/a>\u00a0(Solar Wind with Hydrogen Ion charge Exchange and Large-Scale Dynamics) center \u2014 one of NASA’s\u00a0DRIVE<\/a>\u00a0(Diversify, Realize, Integrate, Venture, Educate) Science Centers \u2014 trace the trajectory of the heliosphere, the massive bubble created by our Sun that envelops our solar system, as it moved through our galaxy and influenced Earth\u2019s climate along the way. In another paper, a NASA scientist and coauthors investigate how the younger, dimmer Sun managed to heat Earth by seeding the production of potent greenhouse gases.<\/p>\n Over the last\u00a0tens\u00a0of\u00a0millions of\u00a0years, Earth\u2019s climate has undergone\u00a0significant shifts, including notable ice ages in which the global average temperature temporarily dropped by several degrees.\u00a0During these periods,\u00a0more frequent\u00a0climate swings\u00a0led Earth to warm and cool.\u00a0To explain these\u00a0periods of warming and cooling, scientists looked to factors internal to Earth, including\u00a0orbital\u00a0changes, greenhouse gases, and ice. But new research suggests changes to the Sun\u2019s environment may be key to understanding Earth’s temperature swings.\u00a0<\/p>\n Just as our planet is encased by an atmosphere, so our entire solar system is encased inside a kind of \u201catmosphere\u201d created by the Sun. This protective bubble, known as the heliosphere,\u00a0is formed by a continuous solar wind of charged particles streaming out from the Sun in all directions.\u00a0<\/p>\n Our\u00a0heliosphere orbits around the center of our galaxy, the Milky Way. Throughout the Sun’s 4.6-billion-year existence, our heliosphere has traversed various regions within our galaxy. In a paper published on Aug. 21 in\u00a0Annual Review of Astronomy and Astrophysics<\/a>, researchers at NASA\u2019s SHIELD used computer modeling to reverse-engineer the path of\u00a0the\u00a0heliosphere through our galaxy, revealing\u00a0that\u00a0the environments it passed through may have\u00a0triggered\u00a0changes on Earth.\u00a0\u00a0\u00a0<\/p>\n Merav Opher, SHIELD\u2019s principal investigator\u00a0at Boston University, and her team ran simulations that showed the Sun has\u00a0encountered\u00a0frigid expanses of gas and dust at least three\u00a0different times\u00a0in the past few million years. In these instances, massive interstellar \u201ccold clouds\u201d pushed against the heliosphere to such an extent that it shrank to smaller than Earth\u2019s orbit, stranding our planet outside the Sun\u2019s protective shield.\u00a0<\/p>\n These exposures \u2014\u00a0approximately 2 to 3\u00a0million years, 6 to 7 million years, and 13 to 14 million years ago \u2014 would have exposed Earth\u2019s atmosphere to\u00a0totally different\u00a0surroundings. The simulation results\u00a0match\u00a0geologic evidence:\u00a0Elements prevalent in interstellar dust\u00a0appear\u00a0in deep-sea sediment core samples, Antarctic snow, and lunar samples\u00a0during\u00a0these timelines.\u00a0<\/p>\n These\u00a0heliosphere collapse events may also explain\u00a0ancient\u00a0climatic\u00a0patterns\u00a0on Earth.\u00a0In the simulations,\u00a0when Earth\u2019s atmosphere was exposed to a cold, dense galactic hydrogen cloud, it increased water vapor content and shifted upper-atmospheric dynamics,\u00a0ultimately altering the conditions at the surface. In summary, our heliosphere\u2019s trips through colder regions in our galaxy may be a key factor in driving some of Earth’s ancient changes in climate, including possible ice ages. \u00a0<\/p>\n The SHIELD center is\u00a0one of several\u00a0that\u00a0NASA funds to unlock the next generation of\u00a0heliospheric\u00a0research. As a DRIVE Science Center, SHIELD builds a team of researchers with differing\u00a0expertise, approaches, and opinions to develop a model, or \u201cdigital twin,\u201d\u00a0of the heliosphere that helps reveal how the heliosphere interacts with its surroundings, including dense interstellar clouds. Understanding our unique, habitable solar system will help unravel the mysteries of life\u2019s evolution on Earth and potentially uncover other habitable\u00a0star systems.\u00a0<\/p>\n In another paper, Vladimir\u00a0Airapetian, a scientist at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland,\u00a0focuses on a long-standing mystery of how the ancient Sun warmed early Earth enough to sustain life. Three billion years ago, the young Sun was 70% as bright as it is today. Under these dimmer conditions, Earth should have been frozen solid. Yet geological evidence shows stable liquid water already existed long before that. This puzzle \u2014 a\u00a0balmy Earth under a cooler, dimmer Sun \u2014\u00a0is\u00a0known as the Faint Young Sun paradox.\u00a0\u00a0<\/p>\n One clue to resolving the paradox comes from young Sun-like stars elsewhere in the galaxy. These \u201ctoddler\u201d stars are prone to throwing fits. Specifically, data from NASA\u2019s\u00a0retired\u00a0Kepler space telescope<\/a>\u00a0shows\u00a0that young Sun-like stars regularly erupt with massive superflares, flinging high-energy particles in all directions\u00a0on a daily basis. If our young Sun\u00a0was\u00a0like these other stars,\u00a0Airapetian\u00a0proposes, the barrage of high-energy solar particles could have triggered chemical reactions that were key to warming early Earth.\u00a0<\/p>\n Airapetian’s\u00a0team simulated early Earth’s atmosphere\u00a0in\u00a0a sealed chamber, mixing molecular nitrogen, ammonia, carbon dioxide, and carbon monoxide. They then fired protons into the mixture, simulating the\u00a0onslaught\u00a0of particles from superflares. This proton bombardment triggered several changes including the\u00a0production of\u00a0nitrous oxide, a greenhouse gas 300 times more potent than carbon dioxide. The research was published in Astrophysical Journal Letters<\/a>.<\/p>\n This\u00a0nitrous oxide\u00a0could help Earth hold onto heat.\u00a0But not all the\u00a0nitrous oxide\u00a0would last. The young Sun\u2019s intense ultraviolet radiation would break some of it down, splitting the molecule back into nitrogen and oxygen.\u00a0But even if only 10% of the\u00a0nitrous\u00a0observed\u00a0in the experiment survived,\u00a0Airapetian’s\u00a0team\u2019s computer simulations confirmed, it would still warm Earth\u2019s equatorial regions to about 41 degrees Fahrenheit (5 degrees Celsius), above water\u2019s freezing point. This smaller amount of\u00a0nitrous\u00a0could even accelerate prebiotic synthesis: just-above-freezing temperatures have been found to be more efficient for building complex chains of amino acids than warmer temperatures.\u00a0<\/p>\n Together, these two studies\u00a0show that\u00a0the Sun\u00a0can\u00a0lead to surprising implications for Earth. While\u00a0our planet\u00a0stands alone\u00a0in many ways, it\u00a0was formed and\u00a0has always existed\u00a0as part of a star-planet system.\u00a0Understanding\u00a0that unique relationship promises new insights about both Earth and the star that sustains it. \u00a0<\/p>\n By\u00a0Desiree Apodaca<\/strong><\/a><\/strong> and Miles Hatfield<\/strong>\u00a0<\/a>
NASA\u2019s Goddard Space Flight Center, Greenbelt, Md.<\/strong>\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"At the center of our solar system, the Sun influences every planet\u00a0that\u00a0orbits\u00a0it.\u00a0In two recent NASA-funded studies, scientists uncovered\u00a0how\u00a0ancient…\n","protected":false},"author":2,"featured_media":654785,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[270],"tags":[65805,6599,7844,18,5198,11511,13998,122411,23373,19,17,19758,133,13390,451,9624,6420],"class_list":["post-654784","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-climate-modeling","tag-earth","tag-earth-science","tag-eire","tag-goddard-space-flight-center","tag-heliophysics","tag-heliophysics-division","tag-heliophysics-research-program","tag-heliosphere","tag-ie","tag-ireland","tag-kepler-k2","tag-science","tag-science-mission-directorate","tag-space","tag-the-solar-system","tag-the-sun"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/117153532897881378","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/654784","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=654784"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/654784\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/654785"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=654784"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=654784"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=654784"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}