Our puzzling Sun

It might be our nearest star, but there’s still much we're trying to work out about it

What’s powering the solar cycle?

Astrophysicists agree that the solar cycle is driven by a solar dynamo – the flowing, electrically charged gas that’s within the Sun, and of which generates its magnetic field and causes fluctuations that trigger solar explosions.

Why’s the corona so hot?

A fire feels warmer the closer you get to it, so in theory, the core of the Sun should be hotter than its surface. Strangely, though, the corona – that’s the outermost layer of the Sun – is far hotter than its surface, and by quite a few millions of degrees more. Why the corona is so hot is still debated, with some suggesting that the Sun’s magnetic fields heat this part of the Sun, while others propose that solar waves are doing it.

Why does the Sun have

long periods of calm?

The solar cycle appears to go on vacation for roughly 70 years. For example, only 50 sunspots

were seen during the ‘Maunder Minimum’ between 1645 and 1715, when some 40,000 to 50,000 were expected. Research has revealed that similar phases of suppressed activity have occurred in the past 10,000 years, but why this occurs remains unclear – although some models suggest that the solar dynamo

revs solar cycles up and down.

Why isn’t it erratic like its stellar

siblings?

Many stars like our Sun actually behave much more erratically than our nearest

star. It’s been observed that more than half of Sunlike stars either have cycles that are slowly increasing,

or decreasing, in how active they are over time.

That’s in comparison to other stars being steady or

completely irregular.