Australian Sky & Telescope March - April 2021

OUR SENSE OF SIGHT is perhaps the most precious of our senses. It not only enables most of us to function in the everyday world, it also lets us experience the wonder of the universe in which we live. For those of us who have sight, imagine if we couldn’t see the Moon or a meteor, a galaxy or a nebula, or simply the amazing starfields of the Milky Way? Imagery has opened our eyes to the splendour of the cosmos and all that’s in it. And of course it’s one of the primary scientific tools for understanding all of the processes that began and continue to guide the evolution of all that is out there. And how marvellous it is that we live in an age when amateur astronomers…

Arecibo collapse signals the end of an era ON THE MORNING OF DECEMBER 1, a rumble echoed through the hilly terrain surrounding Arecibo, the iconic 305-metre-wide radio telescope nestled in a natural sinkhole in Puerto Rico. The 900-tonne receiver platform that had been suspended above the dish had come crashing down. While no injuries occurred, the collapse ended hopes for a controlled dismantling of the telescope, which National Science Foundation (NSF) officials had announced less than two weeks earlier after two unexpected and devastating events that compromised the safety of the telescope. First, an auxiliary cable, which helped suspend the receiver platform, tore out of its socket on August 10, gashing the dish below. A redundant design transferred the load of that auxiliary cable to the four original cables and…

Streetlights and pollution A study led by Christopher Kyba (GFZ German Research Centre for Geosciences) shows that while streetlights are an important source of light pollution, they’re far from the only culprits. The city of Tucson, Arizona, has connected more than 19,000 LED streetlights in a ‘smart city’ control system. From March 29 to April 7, 2019, Kyba and colleagues manipulated public lighting in Tucson, then took overhead images using the Suomi National Polar-orbiting Partnership satellite. They found that Tucson’s streetlights contribute less than 20% of light escaping to space; the rest comes from other light sources such as carparks and billboards. Tucson’s streetlights have full cut-off shielding, which gives the city darker skies than most; nevertheless, the study, published October 28 in Lighting Research & Technology, suggests that fixing…

We’ve known of the existence of ‘minor planets’ or asteroids in the Solar System since the start of the 19th century, when Ceres, Vesta and some others of the largest ones were first detected. Since then the number known, large and small, has grown to many hundreds of thousands, most of them orbiting the Sun in the asteroid belt between Mars and Jupiter (see page 20). For most of that time, these celestial bodies were merely points of light through our largest telescopes, just as the other planets had been before the invention of the telescope 400 years ago. Analysing the light reflected from asteroids using spectroscopes provided insights as to their composition, but they are so small and so far away that for a long time we were unable…

Every year the Auckland Astronomical Society holds the Harry Williams Astrophotography Competition, and each year it attracts the most amazing photos from some very talented astrophotographers, each of them sharing their views of the cosmos as seen from under New Zealand’s pristine dark skies. On these pages we present just a taste of some of the winning imagery, as judged by world-renowned photographer, Babak Tafreshi. You can see the full set of winning images at astronomy.org.nz. Australian Sky & Telescope is proud to be a sponsor of the competition.…

AFTER A SIX-YEAR JOURNEY of 5.24 billion kilometres, the Japanese Aerospace Exploration Agency’s (JAXA) Hayabusa 2 mission returned to Earth on December 6, releasing its sample-return capsule during Earth flyby. Aboard was the precious ‘treasure chest’ containing samples of asteroid 162173 Ryugu. “We started to develop Hayabusa 2 in 2011, and since then, the dream has come true,” says Hitoshi Kuninaka (ISAS/JAXA) during a (translated) press conference. “We performed the mission 100%… and the operations team did a very good job.” The sample release began when the capsule separated from the spacecraft. Spinning once every three seconds, the capsule hit Earth’s atmosphere at a speed of 12 kilometres per second (43,000 kph). JAXA astronaut Soichi Noguchi actually saw the capsule from aboard the International Space Station. The Saji Observatory in…