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Skywatching

Dancing close to the sun

Almost all the solar information we have is either acquired from instruments located on Earth, or in near-Earth space.

This raises two issues.

  • We are too far away to see many of the fine details necessary to understand what the Sun is doing.
  • We infer conditions on the Sun through interpretation of light, radio waves and other solar emissions.

It would be useful to go to the Sun, to measure the solar environment directly, to check if our thinking is right, or to correct what we are getting wrong.

Two spacecraft have been sent to the Sun to meet these needs. One is the European Space Agency's Solar Orbiter; the other is NASA's Parker Solar Probe.

The Solar Orbiter's path around the Sun takes it within 43 million kilometres of the solar surface, giving us sharper and more detailed images than we have ever had. 

It will be exposed to about 12 times the level of heat and radiation we encounter on Earth.

The Parker Solar Probe passes much closer to the Sun, dipping down to within seven million kilometres, in order to sample solar material and magnetic fields directly.

It will be exposed to more than 40 times more heat and radiation than Solar Orbiter does.

In addition to the technical problems involved with building spacecraft to survive such missions, dropping spacecraft so close to the Sun requires very big launcher vehicles and some very clever gravitational manoeuvring.

We are very interested in the Sun for two reasons.

  • It is the only star close enough for easy observation, making it the reference case for our studies of other stars.
  • The Sun provides all our light and heat, making our world habitable, and its bad behaviour can degrade or destroy the technical infrastructure on which our modern lives depend.

For example, in November 1989, a solar flare and coronal-mass ejection caused a massive power outage in Quebec, along with other damage. The total impact was around $2 billion.

This is why nations around the world are investing in solar monitoring programmes, using instrumentation on the ground and in space.

We make two main sorts of measurements of the Sun. There are "sun as a star" measurements, where we monitor some aspect of the Sun as a whole — for example, counts of sunspots or measurements of the 10.7cm solar radio flux, which Canada has made since 1947.

These, continued over years, help us understand the behaviour of the Sun as a star, and to assess the impact of long-term solar behaviour on climate and other environmental factors here on Earth.

The other sort of measurements are conducted over shorter periods, but tell us things that help us check whether our understanding of solar processes is anything like correct.

The better our knowledge of how the Sun works the better we will comprehend what our long-term solar monitoring is telling us.

The environments the Solar Orbiter and the Parker Sun Probe are having to tolerate will mean they are not likely to provide long-term data.

However, they are already giving valuable information about what is happening on the small scales unobservable from the Earth, making it possible to check our understanding of the magnetic machine in the Sun. 

In addition, we are at last getting direct measurements of the environmental conditions in the solar atmosphere, as opposed to inferring them from observations made from Earth.

However, measurements made from the ground are vital in that we can make them consistently and for long periods of time; we just need to be sure we understand as much as possible what we are measuring.

  • Saturn and Jupiter lie low in the southern sky overnight
  • Mars rises around 11 p.m.
  • Venus, shining even brighter than Jupiter, rises around 3 a.m.
  • The Moon will be new on the 18th and will reach First Quarter on the 25th.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.



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About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected]



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The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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