Astronomical distances can be mind boggling. Our closest neighbour, the Moon, is 380,000 kms away — equal to about 10 trips around Earth’s equator.

The closest planet, Venus, is always at least a hundred times farther. And the closest neighbouring star system, Alpha Centauri at a distance of 4.25 light years, is about a million times farther still.
Yet even that enormous gulf is nothing more than a hop away compared to the most distant object that’s easily visible to the unaided eye. The Andromeda galaxy is more than half a million times farther than Alpha Centauri — two-and-a-half million light-years.
Like our home galaxy, the Milky Way, Andromeda is a wide, flat disk. The visible part of the disk spans more than a hundred thousand light-years. But powerful telescopes show that stars taper off into space well beyond that, making the disk twice as wide as the Milky Way’s. We see the galaxy almost edge-on, which raises another mind-boggling detail about astronomical distances. It takes the light from the far edge of the disk longer to reach our eyes than the light from the near edge of the disk. So, there’s no way to see the galaxy at a single point in time. Instead, we see different parts of it as they looked over a span of almost a hundred thousand years.
Yet even at such a huge distance from us, the galaxy is so bright that we can see it, faintly, with our own eyes, low in the north-eastern sky. When viewed from a dark sky location, far from city lights, it looks like a faint, fuzzy blob. But that blob is the combined glow of hundreds of billions of stars, seen as it looked more than two million years ago.
The Andromeda Galaxy and our own Milky Way galaxy belong to a group of more than 30 galaxies, called the Local Group. These galaxies move through space together, bound to each other by the invisible strings of gravity. Andromeda's the more impressive of the two. It's bigger than the Milky Way, and it has more stars. And the black hole at its centre is probably more massive than the Milky Way's black hole.

Almost all the other members of the Local Group are companions to either Andromeda or the Milky Way. In fact, both galaxies have grown so big in part by gobbling up smaller galaxies.

Let’s stay in the eastern part of the sky, with the constellation of Cetus, the whale. It’s not the brightest of constellations, so find a nice dark area. For the naked eye observer, there are a couple of interesting objects. The first is the star named Mira. It is the most famous of all the variable stars, changing its brightness over the period of approximately 330 days from well below naked eye visibility that a small telescope is required to spot it to a brightness even seen from bright light polluted city skies. Mira is a star of truly enormous proportions, it is estimated to be some 400 times the diameter of our Sun!

The second object of interest is the star called Tau Ceti. It’s slightly smaller than our Sun and sits just 12 light years from Earth. It’s located just above Mira in the sky.
Astronomers recently announced that the system has at least four planets, and two of them orbit on the edge of their habitable zones, the so-called Goldilocks Zone, the region where liquid surface water might exist. All four are likely super-Earths, and some could potentially even be as big as Neptune.

Tau Ceti’s proximity to Earth has made it a prime target for planet hunters since 1988. It is a tempting target because it’s more like our sun than other nearby stars, like Proxima Centauri — Earth’s nearest star. In 2015, scientists made global headlines when they discovered Proxima b, an Earth-sized planet. But Proxima Centauri is a red dwarf star, which are prone to extreme flares that might extinguish life. Tau Ceti is more stable.

The four planets they found orbit Tau Ceti in 20, 49, 160, and 642 day orbits. All four are super-Earths, with the inner two at least roughly twice as massive as Earth. The outer two are both some four times bigger than Earth. There is a lot more research to be done. The 160-day planet is at the inner edge of the habitable zone — like Venus and very hot — while the 642-day planet is at the outer edge and could be a cold, Mars-temperature zone planet. And since the system is still relatively young, and jam packed with debris, space rocks likely strike the planets 10 times more often than Earth gets hit.

Insomniacs and early risers should venture into the early hours of the morning around the 21st of October. About 3:00am should do it. Whilst Halley’s Comet won’t return again to the inner solar system until 2061, it makes its presence known at this time of year with a meteor shower. The shower isn’t named for the comet, though, but for the region of the sky in which the meteors appear to “rain” into the atmosphere — the constellation Orion.
A meteor shower takes place when Earth flies through the path of a comet, which is a big ball of frozen water and gases mixed with bits of rock and dirt. As the comet gets close to the Sun, some of the ices vaporize, releasing some of the solid particles. Over time, these bits of dust spread out along the comet’s path.

Halley has made a lot of trips around the Sun, so it’s shed a lot of debris, which has spread out all along its orbit. Earth flies through this path every October. As the particles of comet dust hit the atmosphere they vaporize, forming the glowing streaks known as meteors.

The Orionids are pretty reliable, although not usually spectacular. Look to the north-east, about 30o altitude. At their peak, they produce a couple of dozen meteors per hour. This year’s shower should be at its best as it occurs around the period of New Moon. The best chance to see the meteors is to get away from city lights, and hope for some bright ones to puncture the sky ; some might even leave a smoke trail!

The Moon is Full on the 7th of October, at Last Quarter on the 14th, New on the 21st, and at First Quarter on October 30th. Happy observing!

Get an interactive star chart from Heavens Above www.heavens-above.com

Above: The early evening on October 23 looking west. The 2-day old Moon is joined by Mercury and Mars for a very pretty conjunction. All will fit in the view of 7x50 binoculars. (Created with Stellarium software).