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Humanity’s First Visit to a Star

Credit: John Hopkins University Applied Physics Laboratory

NASA’s Parker Solar Probe will expand our knowledge of the origin and evolution of the Sun. Credit: John Hopkins University Applied Physics Laboratory

By David Reneke

A probe will travel through the Sun’s atmosphere, and astronomers have found the fastest-growing black hole known in the universe.

NASA’s historic Parker Solar Probe mission will revolutionise our understanding of the Sun. It will travel through the Sun’s atmosphere, facing brutal heat and radiation conditions.

In order to unlock the mysteries of the Sun’s atmosphere, the probe will use Venus’ gravity during seven fly-bys over a 7-year period to gradually bring its orbit closer to the Sun. It’ll fly through the Sun’s atmosphere, well within the orbit of Mercury and more than seven times closer than any spacecraft has come before.

Flying into the outermost part of the Sun’s atmosphere, the corona, the probe will employ a combination of onboard measurements and imaging equipment to help our understanding of the corona and expand our knowledge of the origin and evolution of the solar wind.

It will make critical contributions to our ability to forecast changes in Earth’s space environment that affect life and technology here, and in a bold manoeuvre the spacecraft will fly close enough to the Sun to watch the solar wind actually speed up.

At its closest approach, the Parker Solar Probe will hurtle around the Sun at approximately 700,000 km/h. That’s fast enough to get from Sydney to Canberra in about 2 seconds!

At its closest approach to the Sun, the front of the Parker Solar Probe will face blistering temperatures that reach nearly 1400°C. The spacecraft will be protected from this heat by an 11.43 cm carbon-composite solar shield. The spacecraft’s heavily shielded payload will, however, be near room temperature.

On the final three orbits, the Parker Solar Probe will fly to within 5 million km of the Sun’s surface. That’s more than seven times closer than the Helios 2 spacecraft, which came within 35 million km in 1976, and about one-tenth as close as Mercury, which is, on average, about 50 million km from the Sun.

The primary science goals for the mission are to trace how energy and heat move through the solar corona and to explore what accelerates the solar wind.

Astronomers Find Fastest-Growing Black Hole Known

Astronomers at the Australian National University have found the fastest-growing black hole known in the universe, describing it as a monster that devours a mass equivalent to our Sun every 2 days.

The astronomers looked back more than 12 billion years to the early dark ages of the universe, when this supermassive black hole was estimated to be the size of about 20 billion suns and was growing by 1% every million years.

“This black hole is growing so rapidly that it’s shining thousands of times more brightly than an entire galaxy due to all of the gases it sucks in daily that cause lots of friction and heat,” said Dr Christian Wolf from the ANU Research School of Astronomy and Astrophysics.

“If we had this monster, known as a quasar, sitting at the centre of our Milky Way galaxy it would appear ten times brighter than a full moon. It would appear as an incredibly bright pin-point star that would almost wash out all of the other stars in the sky. If this monster was at the centre of the Milky Way it would likely make life on Earth impossible with the huge amounts of x-rays emanating from it.”

The SkyMapper telescope at the ANU Siding Spring Observatory detected this light in the near-infrared, as the light waves had red-shifted over the billions of light-years it took to reach Earth. Astronomers were astounded, as these large and rapidly growing black holes are exceedingly rare.

The discovery of the new supermassive black hole was confirmed using the spectrograph on the ANU’s 2.3 metre telescope to split colours into spectral lines. “We don’t know how this one grew so large, so quickly, in the early days of the universe,” Wolf said.

Now, of course, the hunt is on to find even faster-growing black holes. Because these kinds of black holes shine, they can be used as beacons to see and study the formation of elements in the early galaxies of the universe. Wolf said that instruments on very large ground-based telescopes being built over the next decade would be able to directly measure the expansion of the universe using these very bright black holes.

David Reneke is an astronomy lecturer, writer and broadcaster (