{"id":32853,"date":"2022-06-16T00:00:00","date_gmt":"2022-06-16T00:00:00","guid":{"rendered":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/?post_type=purple_issue&p=32853"},"modified":"2022-07-12T14:58:10","modified_gmt":"2022-07-12T14:58:10","slug":"close-upon-the-sun","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/2022\/06\/16\/close-upon-the-sun\/","title":{"rendered":"Close upon the Sun"},"content":{"rendered":"\n

Together, Solar Orbiter and the Parker Solar Probe are giving us our closest ever look at the Sun. With both now in their science phases, Ezzy Pearson <\/strong>updates us on what we\u2019ve already learned and what\u2019s still to come<\/p>\n\n

\"\"
Solar Orbiter (left) and the Parker Solar Probe (right) in orbit around our Sun <\/figcaption><\/figure>\n\n

Although the star at the heart of our Solar System outshines everything else, its very brightness defies attempts to better understand it. Its light blinds any who look at it, while its heat scorches craft that venture too close. Despite this, specialised observatories have allowed solar astronomers to look on from afar over the years.<\/span><\/p>\n\n

But now there are two telescopes giving an up-close view of the Sun. On 26 March, the European Space Agency\u2019s Solar Orbiter probe sailed past the Sun on its closest approach yet, coming within a third of the Earth-Sun distance to our star. And last year, its observing cousin, NASA\u2019s Parker Solar Probe, passed so near to the Sun that it flew through the outer layers of its atmosphere, sniffing out the pristine particles near the solar surface. But despite the pair being closer to the Sun than any other mission, they are looking at the star in two very different ways.<\/span><\/p>\n\n

Big plasma bubble <\/strong><\/h5>\n\n

\u201cSolar Orbiter is a mission to explore the Sun and the surrounding heliosphere \u2013 the big plasma bubble that the solar wind blows into the interstellar medium,\u201d says Daniel M\u00fcller, project scientist for Solar Orbiter at the European Space Agency. \u201cThe driving rationale for Solar Orbiter is to establish the connections between what our home star does in terms of activity and how that manifests itself in the surrounding heliosphere, including the near-Earth environment. We combine measurements of the plasma at the location of the spacecraft with images of the Sun.\u201d<\/span><\/p>\n\n

\"\"
Solar Orbiter\u2019s enormous 83-megapixel image of the Sun can be experienced online at bit.ly\/ZoomIntoSun <\/figcaption><\/figure>\n\n

The mission launched on 10 February 2020, and has spent the last two years looping around our star. It spends much of its orbit at a distance to protect itself from the searingheat, only swooping in every five to six months for a close pass known as perihelion. Using flybys of Earth and Venus to pull its orbit close to the Sun, it now passes just 48.3 million km from our star. <\/p>\n\n

Solar Orbiter has 10 scientific instruments, four of which look directly at the Sun. On 7 March, while at a distance of 75 million km, the spacecraft used them to take the closest ever image of the Sun. It was so close the camera couldn\u2019t fit the whole solar disc in frame, and instead had to take a mosaic of 25 images. In doing so it created a shot 10 times larger than what can be displayed on a 4K TV screen.<\/span><\/p>\n\n

The other six instruments are in-situ experiments, measuring the environment in Solar Orbiter\u2019s location. One particular area the mission is paying attention to is the solar wind, sniffing out the gusts of charged particles as they stream out of the Sun. <\/p>\n\n

\u201cThe solar wind is largely hydrogen and helium, but there\u2019s a sprinkling of other elements, and it\u2019s those that help us make the connection between the solar wind and where it came from,\u201d says M\u00fcller. \u201cWe identify where ions like oxygen and iron are on the Sun, then sniff them in the solar wind. We combine the measurements with the pictures and connect the two, linking what is flying past the spacecraft with what erupted on the Sun a day or two earlier.\u201d<\/span><\/p>\n\n

Although the spacecraft\u2019s mission, and when it will be close to the Sun, are planned well in advance, during those passes it will adjust its focus to whichever area of the Sun is currently active. <\/p>\n\n

\u201cIn March, we had interesting periods where there were major flares,\u201d says M\u00fcller. \u201cThe question was, can we point to where the flares just were, as there is a high likelihood that it will flare again. Hopefully the Sun will collaborate.\u201d <\/p>\n\n

Flight to the poles <\/strong><\/h5>\n\n

It will be a while until we find out if the Sun was working with the Solar Orbiter team, however, as the flyby generated so much data it only finished downloading in May, and is still being processed. <\/p>\n\n

The spacecraft will continue looping around the Sun, using further encounters with Venus to shift its orbit so that it eventually gets to within 0.28 AU (about 42 million km) of the Sun\u2019s surface. It won\u2019t be resting there for long though, as the spacecraft will then enter into a new science phase as it tips its orbit out of the ecliptic, allowing it to get a clearer view of the Sun\u2019s poles \u2013 something no other spacecraft has ever attained before. <\/p>\n\n

\n\n

Parker Solar Probe vs Solar Orbiter <\/strong><\/h4>\n\n

How do the two spacecraft measure up? <\/p>\n\n

\n
\n

Parker Solar Probe <\/strong><\/h4>\n\n\n\n

Closest pass to the Sun: <\/strong>6.2 million km
Launch date: <\/strong>12 August 2018
Mass: <\/strong>685kg In situ instruments: <\/strong>3
Remote instruments: <\/strong>1
Science goals: <\/strong>Investigate the Sun\u2019s corona and solar wind
Temperature: <\/strong>Heat shield can withstand direct heat of 2,500\u00baC
Orbit: <\/strong>Highly eccentric orbit which takes it out to the orbit of Venus between perihelions <\/p>\n\n\n\n

<\/p>\n<\/div>\n\n\n\n

\n

Solar Orbiter <\/strong><\/h4>\n\n\n\n

Closest pass to the Sun: <\/strong>42 million km
Launch date: <\/strong>10 February 2020
Mass: <\/strong>1,800kg In situ instruments: <\/strong>4
Remote instruments: <\/strong>6
Science goals: <\/strong>Investigate solar polar regions and sunspot cycle
Temperature: <\/strong>500\u00baC
Orbit: <\/strong>With gravitational assists from Venus, the probe will rise up 33\u00ba above plane of the Solar System<\/p>\n\n\n\n

<\/p>\n<\/div>\n<\/div>\n\n

\"\"<\/figure>\n\n

<\/p>\n\n

\n\n

The first polar pass is due on March 2025, at an angle of 17\u00ba to the ecliptic, but by July 2029, it should be at 33\u00ba. The hope is that this unique view of the Sun will give a greater insight into the solar cycle, the repeating pattern of activity in which the number of sunspots peaks and then lulls, only to peak once more 11 years after the last maximum. Though the pattern has been recorded for over 400 years, no one knows its cause.<\/span><\/p>\n\n

\u201cIt\u2019s not clear why it has this periodicity of 11 years \u2013 other stars have different periods,\u201d says M\u00fcller.\u201cThere are various theories, but we can only validate them by getting data from the polar regions \u2013 you need a study from high over the poles to see how the magnetic field changes and gets transported. That\u2019s the next big milestone.\u201d<\/span><\/p>\n\n

Solar Orbiter isn\u2019t the only mission getting cosy with the Sun, however, as NASA\u2019s Parker Solar Probe is also diving around the Sun. And if Solar Orbiter gets close to the Sun, then Parker brushes right past it. <\/p>\n\n

Just a month before Solar Orbiter\u2019s closest approach, Parker made its 11th perihelion journey, coming just 5.3 million km from the Sun\u2019s photosphere \u2013 the Sun\u2019s \u2018surface\u2019 layer, which emits the light we can see. This is so close that it actually passes through the outer layer of the Sun\u2019s atmosphere, the corona. <\/p>\n\n

\u201cParker essentially takes a deep breath and flies into the Sun, hopefully coming out in one piece to downlink the data,\u201d says M\u00fcller. On 28 April 2021 at a distance of 18.8 solar radii (13 million km), Parker measured that it had passed the Alfv\u00e9n critical surface \u2013 the point at which solar particles escape the Sun\u2019s magnetic field and become part of the solar wind. This was the first time Parker had \u2018touched the Sun\u2019 and entered the corona. With every pass after, Parker flies through the corona, and can measure the particles and magnetic fields closest to the Sun.<\/span><\/p>\n\n

\"\"
Solar Orbiter and Parker\u2019s orbits are eccentric, making use of Venus\u2019s gravity to shift into new positions <\/figcaption><\/figure>\n\n

The goal of these deep dives is to understand the connection between the corona and the solar wind. However, getting so close means Parker has to withstand the Sun\u2019s intense heat and light. While its carbon-composite heat shield keeps its instruments at room temperature, it can\u2019t do anything about the brightness.<\/span><\/p>\n\n

\u201cIt can\u2019t look at the Sun directly,\u201d says M\u00fcller. \u201cIt only has a camera pointing sideways, where it can look without burning.\u201d <\/p>\n\n

Photos of the wind <\/strong><\/h5>\n\n

The camera in question is the Wide-field Imager for Parker Solar Probe (WISPR), which photographs the solar wind as it blows past. These images show the patterns of bright particles known as streamers flowing throughout the corona, and helps to build a picture of what the wind looks like from within. The extreme orbit also means that Parker can carry just three other instruments to measure the particles and magnetic field around it. But even with its limited arsenal, Parker has managed to make some intriguing discoveries.<\/span><\/p>\n\n

In 2019, when it was still 34 solar radii out, Parker observed strange zig-zag paths of charged particles known as switchbacks. <\/p>\n\n

\u201cThe switchbacks are a reversal of the magnetic field,\u201d says Nour Raouafi, Parker\u2019s project scientist. <\/p>\n\n

\"\"
Switchbacks, rapid flips in the Sun\u2019s magnetic field, were discovered by the Parker Solar Probe <\/figcaption><\/figure><\/div>\n\n
  • \"\"<\/figure><\/li>
  • \"\"
    Parker provided the first closeup views of solar streamers, jets of bright particles within the corona <\/figcaption><\/figure><\/li><\/ul>\n\n

    \u201cWhile our star\u2019s surface is 5,500\u00baC, the corona reaches around one million degrees C, and no one knows why\u201d <\/p><\/blockquote>\n\n

    \u201cThe magnetic field will flip over itself in and out in a matter of seconds or minutes.\u201d Switchbacks were first seen by ESA\u2019s Ulysses spacecraft in the 1990s, but now that Parker has observed them much closer in to the Sun, it has discovered they are far more common than it first appeared. Parker was able to measure that these switchbacks are rich in helium, which can be traced back to magnetic funnels at the base of the corona.<\/span><\/p>\n\n

    Understanding phenomena such as switchbacks is vital to explaining one of the biggest questions surrounding the Sun that Parker hopes to answer. While our star\u2019s surface is measured at a balmy 5,500\u00ba C, the corona reaches temperatures of around one million degrees C and no one knows why. One theory is that jets of fast particles, like those seen in switchbacks, could be responsible. <\/p>\n\n

    \u201cThere are a variety of theories,\u201d says Kelly Korreck, NASA\u2019s Heliophysics programme scientist. \u201cAs we get more and more data to test those theories, we get closer to figuring out switchbacks and their role in the solar wind.\u201d <\/p>\n\n

    Just like Solar Orbiter, Parker is still closing in on its final orbit, with two more flybys of Venus planned to help bring in its orbit so that by December 2024, it will be flying 6.2 million km from the Sun at speeds of 690,000 km per hour. But the most exciting part of its mission will come at a time that no one will be able to predict.<\/span><\/p>\n\n

    \u201cOne thing we\u2019re looking forward to is when Parker Solar Probe flies through one of the huge coronal mass ejections very close to the Sun, and tells us how the solar energetic particles are accelerated to almost the speed of light,\u201d says Raouafi. <\/p>\n\n

    \"\"
    A coronal mass ejection caught by the SOHO spacecraft. The Parker Solar Probe will attempt to fly through one of these to study its acceleration<\/figcaption><\/figure><\/div>\n\n
    Plasma sniffer <\/strong><\/h5>\n\n

    The solar probes will continue their science phases as they spiral closer towards the Sun, and their return will only grow as they can now collaborate together. While Parker takes a direct look at what is happening close to its surface, sniffing the solar wind and plasma, Solar Orbiter can take a wider look at what is going on. At the same time, the existing solar observatories based on the ground and closer to Earth orbit will be able to look at the whole Sun, giving a global view. <\/p>\n\n

    There will certainly be no shortage of things to look at in the coming years, as the current solar cycle is expected to reach its maximum between November 2024 and March 2026. With a growing number of sunspots, flares and coronal mass ejections creating a storm of space weather, all of the world\u2019s solar observers will be watching with interest, trying to discover what makes the solar winds blow. <\/p>\n\n

    <\/p>\n\n

    <\/div>
    \n

    The many eyes observing the Sun <\/strong><\/h4>\n\n\n\n

    A few of the dozens of other solar observatories helping to put the pair\u2019s observations in context <\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n
    Hinode, Japan <\/strong><\/h5>\n\n\n\n

    An Earth-orbiting satellite built in collaboration with the UK and USA, Hinode launched in 2006. Its goal is to understand the link between magnetic fields near the solar surface and the structure of the outer solar atmosphere, as well as understanding the 11-year solar cycle. <\/p>\n\n\n\n

    Daniel K Inouye Solar Telescope (DKIST), USA <\/strong><\/h5>\n\n\n\n

    With a 4m mirror, DKIST in Hawai\u2019i is the largest solar telescope in the world. Its primary goal is to understand the solar dynamo, and it does so by taking high resolution images \u2013 capable of resolving magnetic features 35km in size \u2013 multiple times a second. <\/p>\n\n\n\n

    Solar and Heliospheric Observatory (SOHO), ESA <\/strong><\/h5>\n\n\n\n

    SOHO launched in 1995, with the aim of observing the Sun\u2019s outer layers including the chromosphere and corona. It helps give global context to measurements taken by probes closer in. It orbits the Sun 1.5 million km from Earth, at the L1 gravitational point.<\/span><\/p>\n\n\n\n

    Solar Dynamics Observatory (SDO), NASA <\/strong><\/h5>\n\n\n\n

    Along with Parker, SDO is part of NASA\u2019s Living With a Star programme, which aims to understand the Sun\u2019s influence on Earth and the space around it. Since 2010, the observatory has been taking images of the Sun in 10 wavelengths every 10 seconds. <\/p>\n<\/div><\/section>\n\n

    \n\n
    \"\"<\/figure><\/div>\n\n

    Dr Ezzy Pearson <\/strong>is BBC Sky at Night Magazine\u2019s <\/em>news editor. Her book <\/span>Robots in Space <\/em>is available through History Press<\/p>\n\n

    <\/p>\n\n

    <\/p>\n\n

    Photos: SOLAR ORBITER: ESA\/ATG MEDIALAB; PARKER SOLAR PROBE: NASA\/JOHNS HOPKINS APL;ILLUSTRATION, ESA & NASA\/SOLAR ORBITER\/EUI TEAM; DATA PROCESSING: E. KRAAIKAMP (ROB), NASA, ESA\/ATG MEDIALAB,NSO\/NSF\/AURA, NASA X 3, NASA\u2019S GODDARD SPACE FLIGHT CENTER\/CONCEPTUAL IMAGE LAB\/ADRIANA MANRIQUE GUTIERREZ, NASA\/JOHNS HOPKINS APL\/NAVAL RESEARCH LABORATORY X 2, SOHO (ESA & NASA) <\/p>\n","protected":false},"excerpt":{"rendered":"

    Solar Orbiter and the Parker Solar Probe are giving us our closest ever look at the Sun.<\/p>\n","protected":false},"author":24,"featured_media":33179,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ub_ctt_via":"","purple_page_number":"60","purple_custom_meta_purple_page_number":"60","purple_seq_number":"1","purple_custom_meta_purple_seq_number":"1","purple_source_article":"article_60-1.xml","purple_custom_meta_purple_source_article":"article_60-1.xml","purple_source_issue":"July-2022","purple_custom_meta_purple_source_issue":"July-2022","purple_external_id":"July-2022-60-1","purple_custom_meta_purple_external_id":"July-2022-60-1","purple_issue_code":"|0000086554||","purple_custom_meta_purple_issue_code":"|0000086554||","purple_android_product":"com.im.skyatnight.206","purple_custom_meta_purple_android_product":"2022skyatnightJuly","purple_ios_product":"com.im.skyatnight.206","purple_custom_meta_purple_ios_product":"2022skyatnightJuly","purple_web_product":"","purple_custom_meta_purple_web_product":"","purple_publication_id":"075fab74-0a21-4201-866a-899d6c41c40c","purple_migrated":"","kt_blocks_editor_width":""},"categories":[21],"tags":[14],"featured_image_src":"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/06\/WAUO29E7337485M1ZHFY8684NT4O.jpg","author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/author\/importmanagerhubsprylab-com\/"},"acf":{"readingTimeMinutes":"12","apple_news_title":""},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/06\/WAUO29E7337485M1ZHFY8684NT4O.jpg",2048,1456,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/06\/WAUO29E7337485M1ZHFY8684NT4O-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/06\/WAUO29E7337485M1ZHFY8684NT4O-300x213.jpg",300,213,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/06\/WAUO29E7337485M1ZHFY8684NT4O-768x546.jpg",768,546,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/06\/WAUO29E7337485M1ZHFY8684NT4O-1024x728.jpg",800,569,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/06\/WAUO29E7337485M1ZHFY8684NT4O-1536x1092.jpg",1536,1092,true],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/06\/WAUO29E7337485M1ZHFY8684NT4O.jpg",2048,1456,false]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"Solar Orbiter and the Parker Solar Probe are giving us our closest ever look at the Sun.","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/32853"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/users\/24"}],"replies":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/comments?post=32853"}],"version-history":[{"count":12,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/32853\/revisions"}],"predecessor-version":[{"id":33420,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/32853\/revisions\/33420"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media\/33179"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media?parent=32853"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/categories?post=32853"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/tags?post=32853"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}