Australian Sky & Telescope

Australian Sky & Telescope August/September 2019

Australian Sky & Telescope is a world-class magazine about the science and hobby of astronomy.  Combining the formidable worldwide resources of its venerable parent magazine with the talents of the best science writers and photographers in Australia, Australian Sky & Telescope is a magazine produced specifically for the Southern Hemisphere’s astronomers.

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1 minutos
returning to that orb in the sky

AS WE CONTINUE the 50th anniversary celebration of the Apollo 11 lunar landing mission, it’s interesting to reflect on how it all came about. Although the human race has always been fascinated by our nearest celestial neighbour and people had long dreamed of journeying to it, it wasn’t until the mid-20th century of course that the capability was developed to get us there. But why was the decision made to send people to the Moon in the first place? As John Sarkissian’s article makes clear (p.18), it was purely a Cold War effort in one-upmanship between the USA and the Soviet Union. Science wasn’t even on the agenda until leading researchers began lobbying the US government to take advantage of this unique opportunity to gather lunar samples and conduct in…

2 minutos
apollo-era data reveal the moon’s tectonic activity

A NEW LOOK AT OLD SEISMIC DATA gathered during the Apollo missions reveals that young active faults might be the source of shallow moonquakes. When the Apollo astronauts deployed seismometers on the lunar surface, they revealed 28 shallow, but sometimes surprisingly powerful, quakes between 1969 and 1977. A new study appearing in the journal Nature Geoscience links these quakes to current tectonic activity on the Moon. As the Moon loses heat from its interior, it shrinks and its surface wrinkles. Thrust faults form where the brittle crust breaks: One side of the break slips downward while the other side goes upward, a process that creates steep slopes, or scarps, typically tens of metres high. Even though these faults cover most of the lunar surface, they had largely gone undetected until 2010, when NASA’s…

2 minutos
omega centauri is losing its stars

ASTRONOMERS HAVE DISCOVERED a stream of stars pulled from Omega Centauri, the largest and most brilliant globular cluster on the outskirts of the Milky Way — and perhaps the remnant of a one-time dwarf galaxy. Omega Centauri is unusually luminous and massive. What most puzzles astronomers, though, is that its stars separate into multiple populations, suggesting that the cluster came together over billions of years instead of all at once. These peculiarities have led some astronomers to suggest that this globular might actually be the remains of a galaxy that came too close to the Milky Way. As it was torn apart by our galaxy’s gravity, most of its stars would have streamed away, looping around the galaxy. Rodrigo Ibata (University of Strasbourg, France) and colleagues reported new evidence for this…

1 minutos
in brief

Beresheet crash-lands on the Moon Israeli company SpaceIL attempted to land Beresheet (Hebrew for ‘in the beginning’) on the Moon on Thursday, April 11. Launched on February 22, 2019, the Beresheet mission took six weeks to reach the Moon, using a series of orbital boosts that elongated its orbit for capture by the Moon’s gravity on April 4. While the first phases of the descent went off without a hitch, the lander began having trouble with its main engine. Although the team was able to re-establish contact and restart the engine at an altitude of about 150 metres, it was too late. Final telemetry showed that the lander was still going 1,080 m/s (3,800 kph) when it slammed at a low angle into the lunar surface. The Lunar Reconnaissance Orbiter later imaged…

2 minutos
ligo and virgo find possible black hole–neutron star crash

ONLY TWO MONTHS INTO a new observing run, gravitational-wave observatories have announced 13 new candidate signals — one of which could turn out to be a black hole swallowing a neutron star. Major improvements to both the Laser Interferometer Gravitational-wave Observatory (LIGO) in the US and the Virgo instrument near Pisa, Italy, have made all three detectors far more sensitive to ripples in spacetime. And beginning with the third observing run, which goes from April 2019 to April 2020, LIGO and Virgo are announcing gravitational-wave signals as they happen — that is, before the sources themselves are fully vetted and confirmed as real. Finding electromagnetic radiation from these candidate events is crucial to understanding them, and immediate announcements enable astronomers to observe the sky near candidate sources at once. Of the 13…

2 minutos
astronomers find universe’s first type of molecule

ASTRONOMERS OBSERVING NEARBY interstellar space have finally detected helium hydride (HeH+ ), the first molecule to form in the early universe. Rolf Güsten (Max Planck Institute for Radio Astronomy, Germany) and colleagues report the find in the scientific journal Nature. The early universe contained mostly hydrogen and helium, so it’s perhaps unsurprising that its first molecule would be helium hydride. But of all the elements, helium requires the most energy to remove an electron — it’s no easy feat for it to combine with another atom. Indeed, the ion didn’t survive long even in the unique conditions of the early universe, but it played a brief but important role. Its destruction gave rise to molecular hydrogen (H2 ), which eventually permeated galaxies and star-forming reservoirs. The existence of HeH+ is thus…