最も近距離で捉えた太陽　欧米探査機が撮影

【パリＡＦＰ＝時事】欧州宇宙機関（ESA）は16日、米航空宇宙局（NASA）と共同開発した太陽探査機「ソーラーオービター」が宇宙観測史上最も近距離で撮影した太陽の画像を公開した。（写真は無人探査機「ソーラーオービター」が撮影した太陽。欧州宇宙機関提供）
　ソーラーオービターは、影響が遠く地球にも及ぶ太陽風と太陽フレア（太陽面爆発）の調査のため、今年２月に米フロリダ州ケープカナベラルから打ち上げられた。
　同機は先月、最初のフライバイ（接近飛行）を完了し、太陽表面近くの現象の詳細撮影に初めて成功。今まで一度も撮影されたことがなかった「キャンプファイア」と呼ばれる小規模な太陽フレアを数十回にわたり観測した。
　太陽風は、太陽フレアにより電気を帯びた粒子が大量に放出される現象。地球を含む惑星に影響を及ぼすが、数十年にわたる研究にもかかわらず不明なことが多いままとなっている。
　ソーラーオービターは最初の軌道周回で太陽の表面からおよそ７７００万キロメートル、地球と太陽の間の約半分に相当する距離に接近した。５００度の高温、地球上と比べて１３倍強い太陽光にも耐えられる設計となっており、最終的には４０００万キロの距離まで迫る計画だ。
　ソーラーオービターによる調査は、最長で９年に及び、その費用は約１７億ドル（約１８２０億円）に上るとみられている。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2020/07/17-11:03）

Scientists said Thursday they had obtained the closest ever images taken of the Sun as part of a pan-European mission to study solar winds and flares that could have far-reaching impacts back on Earth.
The European Space Agency's Solar Orbiter blasted off from Florida's Cape Canaveral in February and completed its first fly by of our star last month, sending back unprecedented images of phenomena close to its surface.
The first images are exceeding our expectations, said Daniel Muller, Solar Orbiter project scientist at ESA.
We can already see hints of very interesting phenomena that we have not been able to observe in detail before.
This makes us confident that Solar Orbiter will help us answer profound open questions about the Sun.
In particular, the team observed dozens of miniature solar flares, known as campfires, which until now had never been captured on film.
David Berghmans, from Belgium's Royal Observatory, said the campfires were several million times smaller than solar flares, which can be observed from Earth.
The Sun seems relatively calm on first viewing but when you look at it in detail you can see miniature eruptions everywhere, he said.
Solar winds and flares emit billions of highly charged particles that impact planets, including Earth. But the phenomena remain poorly understood despite decades of research.
The largest solar storm on record hit North America in September 1859, knocking out much of the continent's telegraph network and bathing the skies in an aurora viewable as far away as the Caribbean.
Solar ejections can also disrupt radar systems, radio networks and can even render satellites useless, though such extremes are rare.
During its first orbit, the craft -- developed in conjunction with NASA -- travelled around 77 million kilometres (48 million miles) from the surface, about half the distance between the Sun and Earth.
Equipped to withstand temperatures as high as 500 degrees Celsius (930 Fahrenheit), it will eventually travel as close as 40 million kilometres from the surface, protecting its instruments with a heat-resistant structure that will be exposed to sunlight 13 times stronger than on Earth.
Its operators plan to gradually tilt the craft's orbit, enabling scientists to obtain the first ever images of the Sun's poles.
The Solar Orbiter mission and is set to last up to nine years at a cost of some 1.5 billion euros ($1.7 billion).