太陽フレアと地球への影響
⽚岡⿓峰
2018年11⽉16⽇（⾦）

アラスカの、満天から降ってくるような星くずを背景にオーロラはゆらめいていた。私は、人間がもし第三の眼を頭の上に付けている動物であったなら、世界観は変って、馬鹿々々しい戦争など、地上から消えるのではないかと思った。
斎藤尚生『オーロラ・彗星・磁気嵐』（1998）

2

内容
１．オーロラとは
２．オーロラの3要素• 復習クイズ３．本番：オーロラのダークサイドについて100年前の発⾒：オーロラはどこで光っているのか？

Carl Störmer (1874‐1957)

http://en.wikipedia.org/wiki/Carl_St%C3%B8rmer

2011.03.03 R2‐D2 Test Experiment @Poker Flat Research Range

www.aurora3d.jp

2012.12.12 R2‐D2 3D Experiment @ Aurora Borealis Lodge

Fish‐eye cameras at Point A and Point B

世界初、オーロラ⽴体視映像

Kataoka et al. (2013)2013.12.21 3Dオーロラ上映＠科学技術館シンラドーム （写真：読売新聞）

2014/10‐2015/02 科学博物館「ヒカリ展」

3Dオーロラシアター

2014/10/16 VR展⽰＠南極・北極科学館

Kataoka et al. (2013)

オーロラは、⾒えない⼤気の層を、⾊付けして⾒せてくれていた（ほぼ真空で起こる）

オーロラ発光の仕組み
(km)
400

電⼦
エネルギーUP！↑↑
エネルギーDOWN↓↓
酸素や窒素↑

光←磁⼒線

1000〜〜

地上オーロラの⾊は⼤気の⾊50年前の発⾒：オーロラは⼤きな環だった

オーロラは環になっている

現在：オーロラは巨⼤な宇宙発電だった

スパコンで再現・予測の時代

現在：オーロラは巨⼤な宇宙発電だった

太陽⾵が発電機を回している。

オーロラ発電機の発電量？
• オーロラの発電は、10 MAと100 kV程度なのでTWのオーダー。
• ⼤型の発電所の出⼒はGWだから、発電所1000基分。
• クイズ：メガ、ギガ、テラはわかりますね。つぎは？

• ⼈間活動を賄える電⼒は、いつも⾃然に出来ていて近くにあった。
• 発電所の電気はその程度、という気づき• 地球は電気の星だった• ⼤⾃然のエネルギーの使い⽅とは？

１．オーロラとは？まとめ• 100年前の⼤きな発⾒• オーロラは宇宙と⼤気の境界で光っていた• 50年前の⼤きな発⾒• オーロラは環だった（環は爆発する）• 現在• スーパーコンピュータで再現・予測の時代• オーロラの再現に必要なのは3つだけ

２．オーロラを作る3つの要素？

aurora3d.jp
ヒントは絵の中に。

太陽⾵、地磁気、⼤気、です。

aurora3d.jp
太陽⾵は⼤気にぶつからない。途中に地球を守る壁（地磁気）があるため。
太陽⾵と地磁気が作⽤して電流が⽣まれ、その電流が⼤気中でオーロラを光らせる。

復習○×クイズ• オーロラは、太陽⾵が⼤気に衝突して光る

復習○×クイズ• オーロラは、太陽⾵が⼤気に衝突して光る• 間違い。太陽⾵は⼤気に衝突しません。
• オーロラは磁気圏の発電で光っています。

１．太陽⾵が磁気圏という発電機を回して電流が複雑に流れる。
２．電流を担う電⼦が集中した場所がオーロラとして確認できる。

素朴な疑問：⽇本でオーロラは⾒られる？

３．オーロラのダークサイド

宇宙災害のフローチャート

3. Darkside of aurora• Introduction• 1859 Carrington event and 1770 Kyoto event• Power outages• 1989 Hydro‐Quebec event• Radiation dose
• 2003 Halloween event• Summary1859 Carrington event• 1859 Sep 1, Carrington
watched a flare duringsketching huge sunspots• 1859 Sep 2, Aurora allover the world.
• Spark discharges atseveral telegraph offices• The largest magnetic
storm for last 200 years• If it occurred now,
economic loss of $1‐2
trillion expected

Carrington (1859)

Kimball, 1960
Large extent of auroral oval ~ large magnetic storm

30

20
10Courtesy of Matsusaka City

“Rays to the north, reach to the zenith”

1770 Kyoto event?
• 1770 September 17• The largest number (>100) of old diaries about
witnessing red auroras in Japanese history• Even larger number of records than Carrington event• 1770 September 16• Captain James Cook and Joseph Banks watched red
aurora in the southern hemisphere around Indonesia.

• 1770 September 16‐18• Red auroras were observed in China for three days
• Similar prolonged events (= very eruptive Sun) can also
be found in “Meigetsuki” in 13th century

What we learn from the history• Japanese old literatures of >1000 years tell us many
important things• The historically great (and very rare) magnetic storms can beidentified to fix the geophysical fact,• which is necessary to understand the great poet Fujiwara‐no‐Teika, as well as to understand transitions of citizen’s mind tofear natural disasters and their view of nature.

• Carrington‐class “dangerous” magnetic storms occurredat least twice within 100 years.
• 150 years have already passed since the Carrington event.
Modern society is vulnerable to the space weather hazard
and we have to prepare to save life.

What happens if it occurred now• Infrastructures of modern society are vulnerable tospace weather events• Power grids are sensitive “antennas” to space• Main cause of the economic loss ($1‐2 trillion expected)• We are flying too high• Significant radiation to humans• Many others, including communication failures andsatellite malfunctions.

It was just lucky that the blast went away. If it hit the Earth…

Coronal mass ejection on 2017/9/10

X‐ray images of the Sun

Flare and Coronal Mass Ejection

コロナ質量放出とフレアは違うRemember that aurora is huge MA current, which can deform the global geomagnetic field.

Hydro‐Quebec magnetic storm

The largest magnetic storm for last 50 years

Geomagnetically Induced Current• Earth current: electric current flows on
the ground• Don’t worry. We don’t feel the electric shock
because the ground is better conductor thanhuman• The large variation of the auroral current(magnetic storm) causes large voltage
difference on ground between distantpositions A and B.

AB• If a conductive artificial structure also
connected the positions A and B, theelectric current flows along the structure.
• This is called GIC, which disrupt power grids$12 million transformer at Nuclear Plant

Hazard map of GIC power outage
Hydro‐Quebec accident
in 1989 March event:Within 92 seconds it
brought down almost
the entire grid, knocking
21.5 GW off line. Theblackout lasted morethan nine hours, affected
six million people, andcost $2 billion.
c.f., Hokkaido blackout:order of 1 GW , $2 billion

Halloween event

Coronal Mass Ejections and Solar Protons: artificial eclipse makes you see the coronal activity

Some histories of solar protons• 1972 April 27, Apollo 16 came back from the Moon
• 1972 August 4, solar proton event occurred.
• If astronauts were at the Moon, the dose would be >10 Sv.

• 1989 October 19, astronauts had to shield themselves
at ISS• Comparable solar protons to 1972 August event.
• People enjoyed aurora in Niigata prefecture Japan.

• 2012 July 23, JAXA’s Akatsuki damaged• Comparable solar protons to 1972 August event.
• Solar panels degrade >10 %.
All around the Solar MAX1972 1989 2012

How much dose by solar protons?
• It can exceed lethal dose of 10 Sv for astronauts at theMoon (without atmosphere) or toward Mars
• However, only up to 1 mSv at flight altitude• Not harmful, comparable to abdominal X‐rays• Radiation workers close to “5 mSv rule” have to care
• Airplanes in polar route sometimes reroute (severaltimes/year), mainly to avoid critical communication failures
and to protect electronics etc. It cost only additional fuel.

• Why so safe?

⼤気中の核破砕反応

Ionization rate of the atmosphere

Temporal destructionof the ozone layer（10‐50 km）

Radiation doseat flight altitude(12 km)Summary: Space Disaster• Infrastructures of modern society are vulnerable tospace weather events• Power grids on ground are sensitive to spacehazards, and we are flying too high
• GICs can cause blackouts over US ($1‐2 trillion expected)• Solar protons cause radiation dose above flight altitude• Carrington‐class magnetic storms occurred at least
twice within 100 years.
• Note that 150 years have already passed since theCarrington event.

Question: True or false?
• Magnetic storms are driven by solar flares

Question: True or false?
• Magnetic storms are driven by solar flares• False. Please differentiate flares (light) and blast.
• Magnetic storms are driven by coronal mass ejections.
• Coronal mass ejections also create solar protons tocause radiation dose for aircrews and astronauts.