Cosmic Howlers
June 2023
NOT IN THE RIGHT VEIN
Despite being on the bleeding edge of astronomy, exoplanet science is not just the domain of professional astronomers. (Astronomy Now, 2019, February, p54)
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The word ‘bleeding’ should, of course, be ‘leading’!
THE SHRINKING MOON
The cluster is 95 arc-seconds across, meaning it is three times the size of the full Moon. (JBAA, 123, 372, 2013)
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There are 60 arc-seconds in an arc-minute and 60 arc-minutes in a degree. The size of the full Moon is about half a degree (1800 arc-seconds), so 95 arc-seconds is actually only about one-twentieth the size of the full Moon.
PREDICTING THE NEXT BRIGHT COMET
Oort cloud – is 10,000 au (astrological units) from the Sun. Earth is 1 au from the Sun. (The Times, 2016, April 13, p7)
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The usual confusion between astrology and astronomy! The abbreviation au stands for astronomical unit.
WE MUST BE IMAGINING THE PLEIADES
Clusters disperse on time scales of a few hundred years (Astronomy & Astrophysics, 521, 12, 2010)
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The stars in an open cluster such as the Pleiades disperse over a period of a few million years.
HOT PURSUIT
…Rosetta then chases Comet Churyumov-Gerasimenko through the Solar System at speeds of over 100,000 km/s. (Popular Astronomy, 61, 26, 2014)
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At 100,000 km/s, the Rosetta spacecraft would have been travelling at about one third of the speed of light!
Rosetta used gravity assist manoeuvres to accelerate throughout the inner Solar System and took about twelve and a half years to reach Comet 67P/Churyumov–Gerasimenko. The average orbital speed of the comet is about 16 km/s, so the speed of Rosetta at the various stages of its journey to 67P would have been closer to that value, typically in the range 10 – 40 km/s.