First results from the Parker Solar Probe reveal the Sun's weird magnetic field

The Parker Solar Probe is heading towards the sun.

The Sun is the closest star to our planet and yet we do not know many things about it. To know more about the sun, NASA launched the Parker Solar Probe (PSP) in 2018 towards the sun. The aim of this probe was to understand the atmosphere of the sun in detail. On its way towards the sun, the probe already sent back some data that it collected. Scientists analysed this data and made some striking observations about the sun’s magnetic field. In this post, I will summarise three these first results from the Parker Solar Probe. 

The Sun has a weird magnetic field

The sun, like any other rotating celestial object creates its own magnetic field. When scientific instruments on-board the Parker Solar Probe (PSP) measured this magnetic field, a surprising pattern was observed. There were flips in the direction of the magnetic field, which flows out from the Sun, embedded in the solar wind that erupts from the sun. These reversals, dubbed “switchbacks” last anywhere from a few seconds to several minutes as they flow over PSP. During a switchback, the magnetic field whips back on itself until it is pointed almost directly back at the Sun. 

Among the many particles that perpetually stream from the Sun are a constant beam of fast-moving electrons, which ride along the Sun’s magnetic field lines out into the solar system. These electrons always flow strictly along the shape of the field lines moving out from the Sun, regardless of whether the north pole of the magnetic field in that particular region is pointing towards or away from the Sun. But Parker Solar Probe measured this flow of electrons going in the opposite direction, flipping back towards the Sun — showing that the magnetic field itself must be bending back towards the Sun, rather than Parker Solar Probe merely encountering a different magnetic field line from the Sun that points in the opposite direction. This suggests that the switchbacks are kinks in the magnetic field — localised disturbances travelling away from the Sun, rather than a change in the magnetic field as it emerges from the Sun.

The Sun’s rotation is not very simple

The sun, just like our earth, rotates on its own axis with a certain velocity. Velocity is a vector and has different components, that is to say that velocity can be different in different directions. The radial component of the sun’s velocity – the velocity in the direction away from the centre of the sun was found to be not consistent. This is surprising to scientists and the reasons for it are still unclear. 

The inconsistent radial velocity could explain why some small flares can be seen ejecting from the sun and perhaps also the weird magnetic field.

A dust-free zone around the Sun

The imaging equipment on PSP was able to gather preliminary evidence for a dust free zone around the sun. It could detect thinning of the solar dust from about 11 million kilometres around the sun and towards. Such a dust free zone was previously predicted by scientists but this is the first time any evidence for it has begun to appear. What this dust free zone means, I have no clue. 

Why are these first results from PSP exciting?

These data and many more to come will enable scientists to predict space weather more accurately. Now that many organisations are thinking of space missions and humanity’s next step is to establish bases elsewhere in the solar system, space weather prediction will become more important than ever. 

References

This article was first published on 04 Jan, 2020 and last updated on 21 Jul, 2020.
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