Mike Lockwood

STFC/Rutherford Appleton Laboratory & Southampton University

Our life-giving star: the flow of energy from the Sun to the Earth

BA Festival of Science, York, Monday 10th September 2007

How the Sun Influences Modern Life

How the Sun Influences Modern Life

Galactic Cosmic Rays

Solar Energetic Particles

Satellite Damage

Human Spaceflight Hazards

Sun and Climate Change

How the Sun Influences Modern Life

Galactic Cosmic Rays

Solar Energetic Particles

Satellite Damage

Human Spaceflight Hazards

Sun and Climate Change

The Solar Wind Plasma

A Coronograph is a man-made eclipse with an occulting disc

blocking out the visible surface of the Sun (the Photosphere).

Allows us to observe the hot solar atmosphere, the Corona

Continuous outflow of ionised gas (“plasma”), The Solar

Wind, 1014 kg per day

Events CMEs eject ~1013 kg at about 350 km s-1

(PS watch the comet!)

The “Frozen-in flux” Theorem

Charged particle motions

Magnetic Field

B

( by definition of B )

Lorentz ForceB

B

Emergence of Coronal Magnetic Flux

Loops of magnetic flux

emerge through the surface in

active (sunspot) regions

Some of this flux is “open” rises through

the corona and is frozen-in to the solar wind

outflow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Sun

Solar wind flow is radial

Solar rotation and radial solar wind generates a Parker spiral field structure

Field is “frozen-in” to the solar wind flow

Parker Spiral(an example of frozen-in)

Interplanetary scintillation is the “twinkling” if radio stars caused by irregularities in the solar wind Tomographic reconstructionfrom interplanetary scintillations

Solar rotation and radial solar wind generates a Parker spiral field structure

Co-rotates with the solar corona (every 27 days in Earth’s frame)

Parker Spiral(an example of frozen-in)

A Stellar Heliosphere

interstellar wind

bow shock

heliopause

heliosheath

Hubble observations of the heliosheath behind the bow shock where the heliosphere of LL Ori heliosphere meets its (dense) local interstellar wind in the Orion nebula

Galactic Cosmic Rays

The coronal source flux is dragged out by the solar wind flow to

give the heliospheric

field which shields Earth from galactic cosmic rays

Cosmic Rays Anticorrelation with sunspot numbers

Sunspot Number

Huancauyo – Hawaii neutron monitor counts

(>13GV)

Climax neutron monitor counts

(>3GV)

A Stellar HeliosphereCosmic ray tracks in a bubble chamber

How the Sun Influences Modern Life

Galactic Cosmic Rays

Solar Energetic Particles

Satellite Damage

Human Spaceflight Hazards

Sun and Climate Change

Solar Energetic Protons(SEPs)

Energised at the shock fronts of CMEs (and CIRs)

Follow heliospheric field lines

Seen here striking the imager CCD plate of the LASCO coronograph on the SoHO spacecraft

Sun

Parker Spiral(an example of frozen-in)

Sun

SEPs generated at front of CMEs

Guided along IMF

Parker Spiral(an example of frozen-in)

CME

How the Sun Influences Modern Life

Galactic Cosmic Rays

Solar Energetic Particles

Satellite Damage

Human Spaceflight Hazards

Sun and Climate Change

Spacecraft Damage

spacecraft

penetrating radiation

electronics box

sensitive component

charge buried in insulator can discharge

floating circuit trace can collect charge and

discharge

radiation environment damage:

Surface charging 0.1 – 100 keV electrons

Single event upsets MeV ions

Cumulative radiation dose Limits spacecraft lifetime

Internal charging (“deep dielectric charging”)

MeV electrons

Tomographic reconstruction from interplanetary scintillations

The Bastille Day Storm CMEs seen by IPS

► Ground-level enhancement (GLE) of solar energetic particles seen between Forbush decreases of galactic cosmic rays caused by shielding by the two CMEs

► Here seen at stations in both poles (McMurdo and Thule)

Neutron Monitor counts

Forbush decrease caused by 1st CME

GLEForbush decrease caused by

CME associated with GLE

nm

co

un

ts

The Bastille Day Storm GCRs and SEPs

▲▼ = Single event upsets (SEUs) suffered by satellites in geostationary and high altitude orbits

several satellites were powered down to protect them

The Bastille Day Storm SEPs seen at Geostationary Orbit

How the Sun Influences Modern Life

Galactic Cosmic Rays

Solar Energetic Particles

Satellite Damage

Human Spaceflight Hazards

Sun and Climate Change

BIOLOGICAL EFFECTSBIOLOGICAL EFFECTS

Heavy ions

breaks molecular links

&

can cause nuclear reactions so (e.g.) C converted to N and O in molecules

The Apollo Missions

Above annual dose

Above annual dose

SEPs: just how lucky were the lunar astronauts?

SEPs during the era of the Apollo Missions

Raised cancer risk

Raised cancer risk

Severe radiation sickness

Severe radiation sickness

Instantly fatal

Instantly fatal

Average annual dose at Earth’s surface

Max. annual dose for a radiation worker

SEPs: what’s the space weather been like?

Above annual doseRaised cancer risk

Severe radiation sickness

Instantly fatal

SEPs and Galactic cosmic rays since the Apollo Missions

How the Sun Influences Modern Life

Galactic Cosmic Rays

Solar Energetic Particles

Satellite Damage

Human Spaceflight Hazards

Sun and Climate Change

Total Solar Irradiance

best composite of observations (by PMOD, Davos)

shows 0.1% solar cycle variation

damped out by large thermal capacity of Earth’s oceans but are there century- scale changes which would not be damped?

Total solar irradiance changes and magnetic field emergence

Dark sunspots and bright faculae are where magnetic field threads the solar surface

TSI reconstructions

Open Solar Flux, FS

TSI (for 3 assumptions for the Maunder Minimum)

A. [Fp]MM = [Fp]now

B. [Fp]MM = 0

C. [Fp]MM = [Fp]now /2

Recent trends - revealed by averaging over solar cycle length, L

► sunspot number, R

► FS from IMF data

► GCR counts C (Climax n.m.)

► PMOD composite of TSI data

► solar cycle length, L

running mean over T=[9:(1/4):13] yrs

running mean over T=L yrs