Northern Autumn / Southern Spring

North Autumn South Spring (with Alrescha)-lowThe night sky at this time of year plays host to Cassiopeia, which can be found at or near the overhead point when viewing from mid-northern latitudes. The southern regions of Cepheus, together with its leading star Alderamin and the variable star Delta Cephei, lie just to the west of Cassiopeia. Delta Cephei is the prototype of what is perhaps the most famous class of variable star and was the first star of its type to be recognised. The variations of Delta Cephei were discovered in 1784 by the astronomer John Goodricke, since which time hundreds of Cepheid variables have been found. Cepheids are short-period pulsating variables that are large and very luminous and can be seen over immense distances, their periods of variability ranging between as little as a day to around a couple of months or more. The period of Delta Cephei itself is 5.367 days, during which time it varies between magnitudes 3.5 and 4.3, and it is worth keeping a regular eye on Delta Cephei to check for its changes in brightness.

Just to the south of Cepheus is the tiny constellation Lacerta (the Lizard). Taking the form of a zigzag line of faint stars, Lacerta may not be easy to pick out without some form of optical aid, unlike the bright star Deneb in the neighbouring constellation Cygnus (the Swan), one of the stars forming the Summer Triangle which extends beyond the borders of this chart but which is depicted in full on the chart of Northern Summer / Southern Winter stars.

A little way to the south of Cassiopeia is the line of stars forming Andromeda with Sirrah, the westernmost star in Andromeda, being located at the corner of the adjoining and very conspicuous Square of Pegasus (the Winged Horse). This huge quadrilateral of stars is a striking feature of the night sky at this time of year. If the sky is really dark and moonless you might like to try your hand at counting the number of stars visible to the naked eye within the Square of Pegasus. If viewing conditions are good, you have really keen eyesight, you might spot twenty or more. The rest of Pegasus extends to the west of the Square where, situated immediately to the west of Enif, the brightest star in Pegasus, we find the tiny constellation Equuleus (the Little Horse).

Located just to the north east of Andromeda is the bright star Algenib in Perseus, with the famous variable star Algol visible just to the south of Algenib (see Perseus). To the southeast of Andromeda are the two tiny but prominent groups Triangulum (the Triangle) and Aries (the Ram) and extending in a meandering line from Andromeda to below the Square of Pegasus is the large but generally faint constellation Pisces (the Fishes).

To the south of Pegasus we find Aquarius (the Water Carrier), located by following a line from Scheat, through Markab, both in the Square of Pegasus, as shown here. On the way towards the bright star Fomalhaut you will pass just to the east of the star Skat in Aquarius from where you should be able to make out the rest of this large and sprawling constellation. Unless the sky is really dark and clear, you may need binoculars to detect the stars of Aquarius, as well as those forming the constellation Capricornus (the Goat) found immediately to the southwest of Aquarius.

Staying with the watery theme, bordering the south-eastern edge of Pisces is another faint constellation, this being Cetus (the Whale). The whale’s tail is marked by the fairly prominent star Deneb Kaitos, a name derived from the Arabic for ‘Tail of the Whale’. By far the most interesting object in this group is the long-period variable star Mira which is described in more detail on the posting for Cetus.

The bright star Fomalhaut in the constellation Piscis Austrinus (the Southern Fish) derives its name from the Arabic for ‘Mouth of the Fish’. When viewed from mid-northern latitudes, Fomalhaut lies just above the southern horizon during late-evenings in autumn and can be found by following a line southwards from Scheat, through Markab, both in the Square of Pegasus, as shown here. If the sky close to your horizon is exceptionally dark and clear you should spot Fomalhaut and, using binoculars, may be able to pick out some of the fainter stars in Piscis Austrinus together with at least part of the neighbouring Sculptor (the Sculptor) and, further to the east, Fornax (the Furnace).

To the south of Piscis Austrinus we have Grus (the Crane) with its brightest star Alnair fairly prominent. Grus is flanked by the quartet of comparatively faint constellations Microscopium (the Microscope), Indus (the Indian), Tucana (the Toucan) and Phoenix (the Phoenix). Ankaa, the brightest star in Phoenix, is reasonably conspicuous to the southeast of Fomalhaut, as is the bright star Peacock, located in the constellation Pavo (see South Circumpolar Stars) and which can be found close to Indus.

Immediately to the southeast of Phoenix is the southern extremity of Eridanus (the River), marked by its leading star Achernar and depicted in full on the chart of Northern Winter / Southern Summer stars. Achernar is a good guide to tracking down many of the fainter groups in this region of sky including Horologium (the Pendulum Clock), visible as an extended trail of faint stars located nearby.

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