Night Sky Almanac 2023: A stargazer’s guide

Product Information

After Junius, he simply counted the months beginning Quintilis, Sextilis (our July and August). This gave: But then the priests messed things up again. They started counting leap years every three years. The error was corrected by the emperor Augustus and by 8 CE the matter had been solved and the months and the Sun were in agreement. But then the Senate decided to rename one month in honour of Augustus – so the month of Sextilis became our August. Unfortunately, under Caesar’s scheme that month had just 30 days, whereas Caesar’s (our July) had 31 days. Obviously Augustus had to have the same number of days, so they pinched one from poor February, leaving it with 28 days, except in leap years. (At the same time, to avoid having three months with 31 days in succession they also tinkered with the lengths of the months after August, which is why September and November now have 30 days and October and December 31. Sirius, α Canis Majoris (α Cma), in the southern celestial hemisphere, is the brightest star in the sky at magnitude -1.44.

2023: Night sky events not to miss - EarthSky Best of 2023: Night sky events not to miss - EarthSky

February 28 • In the north, the Moon is lining up with Elnath (β Tau), Mars, and Aldebaran. (as seen from Sydney). As it passes across the sky from west to east in its orbit around the Earth, the Moon moves by approximately its diameter (about half a degree) in an hour. Normally, in its orbit, the Moon passes above or below the direct line between Earth and Sun (at New Moon) or outside the area obscured by the Earth’s shadow (at Full Moon). Occasionally, however, the three bodies are more-or-less perfectly aligned to give an eclipse: a solar eclipse at New Moon, or a lunar eclipse at Full Moon. Depending on the exact circumstances, a solar eclipse may be merely partial (when the Moon does not cover the whole of the Sun’s disc); annular (when the Moon is too far from Earth in its orbit to appear large enough to hide the whole of the Sun); or total. Total and annular eclipses are visible from very restricted areas of the Earth, but partial eclipses are normally visible over a wider area. Two forms of solar eclipse occur this year, and are described in detail in the appropriate month. Continuing round from Canopus we pass the constellation of Dorado, the small constellation of Reticulum and the undistinguished constellation of Horologium, beyond which is Achernar (α Eridani) the brightest star in the long, winding constellation of Eridanus, which actually starts far to the north, close to Rigel in Orion. Between Achernar and the SCP lies the triangular constellation of Hydrus, next to the constellation of Tucana which contains the Small Magellanic Cloud (SMC). The most famous carbonaceous chondrite meteorite is probably the Murchison meteorite, observed to fall near Murchison, Victoria, Australia on 28 September 1969. Both Murchison and the recent Winchcombe meteorite belong to the group known as the CM meteorites. Their material appears to resemble that collected by the Hayabusa 2 spaceprobe from the minor planet (162173) Ryugu, and returned to Earth in December 2020. The Murchison meteorite has been particularly important and the subject of numerous, significant studies. It has been found to contain a phenomenal number of molecular compounds (at least 14,000), including some 70 amino acids. Some estimates put the number of potential compounds in the meteorite at hundreds of thousands, or even as high as one million. In January 2020, an international team of cosmochemists announced that some silicon carbide (SiC, carborundum) particles from the Murchison meteorite were the very oldest particles ever detected. They had anomalous isotopic ratios of silicon and carbon, implying that they were formed outside the Solar System. These grains have a suggested age of 7000 million years, some 2500 million years older than the Solar System itself. The charts that are used differ considerably from those found in most astronomy books, and have been specifically designed for use anywhere in the world. A full description of how to use and understand the monthly charts is given here.Why does February have such an odd number of days, and why do we tinker with it every four years? The answer is suprisingly complicated, and involves the ancient Roman lunar calendar, Roman emperors, including Julius Caesar, the Roman Senate, the priests, and the way in which politicians messed about with the calendar, and how we have avoided even greater confusion. A fairly comprehensive description of how these changes came about is given here. About 713 BCE, two more, January (Januarius from Janus, the Roman god of beginnings) and February (Februarius, from Februa, the Roman ritual of purification at the end of the year) were added. The highly distinctive (and widely recognized) constellation of Ursa Major with the distinctive asterism of the Plough (or Big Dipper) is now ‘upside down’ and near the zenith for observers in the far north, for whom it is particularly difficult to observe. At this time of year, it is high in the sky for anyone north of the equator. Only observers farther towards the south will find it lower down towards their northern horizon and reasonably easy to see. However, at 30°S, even the seven stars making up the main, easily recognized portion of the constellation are too low to be visible. August 24: The First Quarter Moon, the season’s best for observing lunar features telescopically, hovers to the right of the famous red supergiant Antares, the alpha starof Scorpius. Such far northern observers will also find that Castor (α Geminorum) is actually circumpolar, although at times it is extremely low on the horizon. The other bright star in Gemini, Pollux (β Geminorum) is slightly farther south and cannot really be considered circumpolar.

NIGHT SKY ALMANAC 2023: A stargazer’s guide - Goodreads NIGHT SKY ALMANAC 2023: A stargazer’s guide - Goodreads

Precautions must always be taken when viewing even partial phases of a solar eclipse to avoid damage to your eyes. Only ever use proper eclipse glasses, or a proper solar filter over the full objective of a telescope. The glass ‘solar filters’ sometimes provided with cheap telescopes should never be used. They are unsafe.The image by Damian Peach was taken with a 14 inch telescope in Barbados where the seeing can be particularly good. This image won the "Astronomy Photographer of the Year" competition in 2011.