Cosmic Howlers
February 2023
DIVINE OBJECTS
Variable stars are used to measure the dimensions and study spiritual structures of remote corners of the vast Milky Way (The New York times, 1956 May 6)
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The word ‘spiritual’ should, of course, be ‘spiral’!
The reference to variable stars relates to their use in determining distances both within and outside our own Milky Way galaxy. A particular type of star used for this is the Cepheid variable – a strong correlation exists between a Cepheid’s intrinsic luminosity and its pulsation period, so by measuring the period its intrinsic luminosity can be determined which, by also measuring its brightness as seen from Earth, can then be used to calculate its distance.
THE CRUX OF THE ERROR
…the north pole faces the same direction in space – towards Polaris –… In the same way, the south pole keeps facing the Southern Cross. (New Scientist, 2022 April 23 p57)
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The Southern Cross (Crux) actually straddles declination 60 degrees south, so it’s well away from the South Celestial Pole!
The North Celestial Pole lies in the constellation Ursa Minor (the Little Bear) and is marked by Polaris (the Pole Star) which lies less than 1 degree away from the pole. Polaris is designated α Ursae Minoris (Alpha Ursae Minoris) and it is easily visible to the naked eye at magnitude 1∙98.
In contrast, the South Celestial Pole lies in the faint constellation Octans (the Octant). The star σ Octantis (Sigma Octantis) is identified as the South Pole Star, although it’s more than one degree away from the pole! Unfortunately, with a magnitude of 5∙5, it’s barely visible to the naked eye.
REMOTE PROSPECT
Some of the earliest findings of exoplanets appeared in our pages, including, in 1995, the first report of an exoplanet orbiting a Sun-like star in another galaxy (Nature, 575, 7, 2019)
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All the exoplanets discovered so far are in our own galaxy – the technology to look for exoplanets in distant galaxies does not yet exist!
The exoplanet referred to in the article was 51 Pegasi b, also called Dimidium (sometimes known as Bellerophon) discovered by Michel Mayor and Didier Queloz who shared the Nobel Prize in Physics for their work. 51 Peg b is a ‘hot Jupiter’ – a gas giant exoplanet – which orbits a main-sequence star, the Sun-like 51 Pegasi.
51 Pegasi b orbits its parent star every four days and has a temperature of approximately 500-1000 degrees C. It’s 51 light-years from the Earth.
THAT DEPENDS ON HOW HARD YOU THROW THEM
Advanced LIGO, housed in tunnels in Louisiana and Washington state, works by measuring how long it takes lasers to travel to a distant mirror (Discover Magazine, January/February 2021, p66)
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The LIGO detectors work by measuring how long it takes laser light – not lasers – to travel to a distant mirror!
CLOSE INDEED
Solar orbiter’s next close perihelion will take place on 13 October, when it will be just 4∙3 million kilometres (0∙29 astronomical units) from the Sun. (Astronomy Now, 2022 July, p16)
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An astronomical unit is a unit of length – roughly the distance from the Earth to the Sun – which is approximately 150 million kilometres (93 million miles) or exactly 149,597,870∙7 km.
The perihelion distance of 0∙29 astronomical units is correct – but this is approximately 43 million kilometres…ten times more than stated in the article!