I am extremely grateful to such sources as: The BBC, Wikipedia, the Encyclopaedia Britannica and the following 3 NASA sources (any brown coloured text) from which I gleaned the statistics, facts, and no small amount of text in my personal article that follows…. https://spaceplace.nasa.gov/craters/en/
Our Near Neighbours And Visitors In Space – How Much Do We Really Know?!
Do WHAT, he said!? Just lie on this sun lounger, flat on your back with your feet facing South, came the reply. Those were the instructions I was told to follow, to see the Geminid meteor shower of approximately December 4th to the 20th, 2024. But it was also during this special month of heavenly activity in and around earth, that my body afflicted me with the worst bout of cold or flu viruses that I’ve had in decades. Now, I know I’m a man (and us Guys do tend to suffer from ‘Man Flu’ way worse than you Gals out there) but, I didn’t feel like getting out of bed, let alone lie outside in the cold! But, for those who had the patience to wait for the masses of England’s clouds to clear during this period, by the pictures that started appearing on various websites, they were obviously rewarded with memorable sights and photographs, all of which, I missed.
A few Geminid facts: The Geminids appear to radiate from near the bright star Castor in the constellation of Gemini. What sets the Geminids apart from other meteor showers is their origin: while most meteor showers originate from comets, Geminids are leftover bits and pieces of the asteroid known as 3200 Phaethon. Unlike comets, asteroids don’t develop tails when approaching the sun, and their composition is different.
Oh well, I told myself, they’ll be around again next year, added to which, will be the great super moon, later in November 2025, – not even I could miss that, surely, however ill I might be!
But all this mention of heavenly bodies, forced me to do a bit of research, so as to better acquaint myself with the subject. I decided not to tax myself too sorely, so I started with our nearest neighbour, THE MOON. And wow, was I rewarded for my miniscule investigations. My starting point was NASA and the 3 web addresses and sites above (and more listed below), but I gleaned lots of little mini facts from loads of other sites along the way. For example, on average, our moon is 238,900 miles (384,472 km) away from Earth, literally, a near neighbour in space terms. And I was staggered at the huge number of different names that have been assigned to our moon, depending on its visible changes in characteristics. I underestimated too, the various cultures and civilisations in history, that have given our moon a whole host of individual, or even monthly names, either of colours or of animals or similar. But, as I started writing this for a bit of fun, I’ll not bore you with the extensive lists I ‘bumped into’. But I’ll start you with an easy moon name…..
A lot of older people in particular, will have heard of the term, BLUE MOON, usually used in expressions like, “that occurs once in a blue moon”. Now, when the expression was first used, way back in the 16th century, it was said to mean that an event was thought to be impossible. But my research told me that, over time, the meaning of that expression blue moon had to be changed several times, the first, following
the 1883 eruption the Krakatoa volcano in Indonesia (see the approx. map location).
This is because, after the prolonged particulate fallout, many people around the world saw strangely coloured sunsets plus a moon that appeared blue. So now, the expression’s meaning shifted to meaning an event that is extremely rare (Krakatoa having only erupted just over 50 times in all recorded history). But over the course of time, as telescopes improved and man’s observations of the moon increased, the definition and meaning changed yet again and you’ll understand why the expression is not so often heard now. This is because, of all the full moons there are, only 3% are designated blue moons. That’s because they are now defined as occurring only when two full moons appear within the same calendar month – so, statistically speaking, it’s not so rare as we first thought. And by the way, the colours associated in some of these moon names, has nothing to do with its actual colour. It depends a lot more on things like: where in the sky the full moon appears to the observer. I.e. the lower it hangs in the sky, the more our atmosphere scatters the shorter blue and violet wavelengths of light, leaving us to observe more of the red end of the spectrum. Other weather events too, particularly sand, blown over from places like the Sahara, can make the skies and heavenly bodies appear more orange. Even far away here in the UK, from where I’m writing this piece, recent studies are predicting that such events will be a more frequent occurrence. Indeed, in February 2021, important concentrations of Saharan dust literally coloured the snow on the Alps orange!
Here's one more name for you: A HARVEST MOON – (occurring at the late September equinox. The equinox itself is set for September 22 each year, but once every 3 years, the full moon actually appears in early October). Such moons were named long before the powerful tractor lights of today, as they gave farmers extra light to work late into the night, during the busy harvest time. But all this talk of the moon started me thinking and asking questions like….
Our Moon – Why Is It So Different From Earth?!
If you look at the moon through any decent telescope, what’s the first thing that’s often commented on? The craters, caused by various asteroids and meteors impacting it at great speed.
Sure, although we only know of about 180 on Earth, we can see many thousands of craters on the Moon. Why is that? And, if the earth is such a near neighbour in space, with presumably, the same likelihood of being hit by a speeding heavenly object, why does the earth show so few? The main difference between the two is that Earth has processes that can erase almost all evidence of past impacts. The Moon does not. Pretty much any tiny dent made on the Moon’s surface is going to stay there.
Three processes help Earth keep its surface crater free. The first is called erosion. Earth has weather, water, and plants. These act together to break apart and wear down the ground. Eventually erosion can break a crater down to virtually nothing. The Moon has almost no erosion because it has no atmosphere. That means it has no wind, it has no weather, and it certainly has no plants. Almost nothing can remove marks on its surface once they are made. The dusty footsteps of astronauts who once walked on the Moon are still there today, and they aren’t going anywhere anytime soon.
The second thing is something called tectonics. Tectonics are processes that cause our planet’s surface to form new rocks, get rid of old rocks, and shift around over millions of years. Because of tectonics, the surface of Earth is recycled many times throughout its long history. As a result, very few rocks on Earth are as old as the rocks on the Moon. The Moon has not had tectonics for billions of years. That’s a lot more time for craters to form and stay put.
The third thing is volcanism. Volcanic flows can cover up impact craters. This is a major way impact craters get covered up elsewhere in our solar system, but it is less important than the
recycling of crust here on Earth. The Moon once had large volcanic flows way in the past that did cover up many of the bigger earlier impacts, but it has been without volcanism for around three billion years.
So, to sum up: The earth and the moon are hit in the same proportions over time, in general, but, because of it’s larger size and higher gravity, about 20 asteroids strike the earth for every one that strikes the moon, though large impacts on either body are rare. The Moon may attract fewer bits of space rock than the Earth, but the Moon is powerless to do anything about it after it has been hit. Once something hits the Moon, that event becomes frozen in time. Earth, on the other hand, simply brushes these impact craters off and moves on with its life. No wonder there are so many craters on the Moon compared to Earth! The Wikipedia pictures shows the Tycho Lunar (Moon) Crater, named after the Danish Astronomer Tycho Brahe.
This has been my early peering into the wealth of information about the moon and our occasional near visitors, and I’ve enjoyed it so much, I’m sure I’ll feel compelled to write more.
Other, lesser used references include: