Image credit: (ESA/Royal Observatory of Belgium)
Something We've Never Seen Before: The Sun's North Pole
A solar mission has given us a glimpse of the Sun’s poles, in the form of an image pieced together from data collected by the European Space Agency's PROBA-2 (PRoject for OnBoard Autonomy 2) satellite, in orbit around Earth.
Earth - and most of the objects in the Solar System - orbits the Sun in a flat disc, close to the star's equator. This is called the ecliptic plane. We launch spacecraft out on this ecliptic plane, for practical reasons. The spin of Earth on its axis gives a rocket a boost, meaning it takes less effort to get it into space. The closer the launch is to the equator, the greater the boost. It would be much harder to launch a rocket from Earth's polar regions. So, rockets launched from Earth are already travelling in the ecliptic plane and therefore normally aren't in a position to peek at the Sun's poles. It is possible to get out of this plane, but it's quite hard and time-consuming. This is the reason why we've never been able to directly see either of the Sun's poles.
There has actually been one probe that looked at the Sun's poles, though: Ulysses, which looped over the top of the Sun's poles at a distance of nearly 322 million kilometres (200 million miles) - but none of its instruments were a camera.
This time, we're not looking at a photograph either, strictly speaking - but it's very close. When spacecraft observe the solar atmosphere, they gather data on everything along their line of sight, also viewing the atmosphere extending around the disc of the Sun, and scientists can use this to infer the appearance of the polar regions. Slice by tiny slice, as the Sun rotates, PROBA-2 takes readings of these elements in extreme ultraviolet wavelengths, then combines them into a reconstruction of the Solar poles.
ESA scientists have been building these images since June this year, uploading them into a database so that they can observe how the Sun's poles change over time. This is so that they can build on the knowledge gleaned by Ulysses, and try to learn more about the dynamics of solar phenomena at the polar regions - such as coronal holes, Alfvén waves and Rossby waves.
For actual photos, we have to wait for ESA's Solar Orbiter, scheduled for launch in 2020. It's not going to orbit the poles, but will zoom around at high-enough latitudes that it will be able to image those mysterious and elusive regions.
Source: https://www.sciencealert.com/here-s-something-you-ve-probably-never-seen-before-the-sun-s-north-pole MICHELLE STARR 4 DEC 2018
Something We've Never Seen Before: The Sun's North Pole
A solar mission has given us a glimpse of the Sun’s poles, in the form of an image pieced together from data collected by the European Space Agency's PROBA-2 (PRoject for OnBoard Autonomy 2) satellite, in orbit around Earth.
Earth - and most of the objects in the Solar System - orbits the Sun in a flat disc, close to the star's equator. This is called the ecliptic plane. We launch spacecraft out on this ecliptic plane, for practical reasons. The spin of Earth on its axis gives a rocket a boost, meaning it takes less effort to get it into space. The closer the launch is to the equator, the greater the boost. It would be much harder to launch a rocket from Earth's polar regions. So, rockets launched from Earth are already travelling in the ecliptic plane and therefore normally aren't in a position to peek at the Sun's poles. It is possible to get out of this plane, but it's quite hard and time-consuming. This is the reason why we've never been able to directly see either of the Sun's poles.
There has actually been one probe that looked at the Sun's poles, though: Ulysses, which looped over the top of the Sun's poles at a distance of nearly 322 million kilometres (200 million miles) - but none of its instruments were a camera.
This time, we're not looking at a photograph either, strictly speaking - but it's very close. When spacecraft observe the solar atmosphere, they gather data on everything along their line of sight, also viewing the atmosphere extending around the disc of the Sun, and scientists can use this to infer the appearance of the polar regions. Slice by tiny slice, as the Sun rotates, PROBA-2 takes readings of these elements in extreme ultraviolet wavelengths, then combines them into a reconstruction of the Solar poles.
ESA scientists have been building these images since June this year, uploading them into a database so that they can observe how the Sun's poles change over time. This is so that they can build on the knowledge gleaned by Ulysses, and try to learn more about the dynamics of solar phenomena at the polar regions - such as coronal holes, Alfvén waves and Rossby waves.
For actual photos, we have to wait for ESA's Solar Orbiter, scheduled for launch in 2020. It's not going to orbit the poles, but will zoom around at high-enough latitudes that it will be able to image those mysterious and elusive regions.
Source: https://www.sciencealert.com/here-s-something-you-ve-probably-never-seen-before-the-sun-s-north-pole MICHELLE STARR 4 DEC 2018
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