In March we\u2019ll be two years away from the 500th anniversary of Ferdinand Magellan\u2019s visit to the Mariana Islands. There will surely be some hoopla when that milestone arrives. If you\u2019re looking to hold a theme party you can\u2019t miss. <\/p>\n
While you\u2019re adjusting your social calendar, some astronomers, thanks again to Magellan, are doing some adjusting of their own. They reckon that a galaxy named after Magellan is on a collision course with our galaxy, the Milky Way. We\u2019re due to get belly-punched in 2.4 billion years, give or take about a billion either way. <\/p>\n
So, eventually, our intrepid Portuguese navigator will get the last laugh.<\/p>\n
The Milky Way galaxy has a number of smaller galaxies that hang out in the neighborhood. Two such galaxies are called the Large Magellanic Cloud and the Small Magellanic Cloud. These are so named because Magellan mentioned them in his notes when he saw them. They are very prominent features of the southern hemisphere\u2019s sky. What looked like fuzzy \u201cclouds\u201d in the night sky were actually galaxies, but the \u201ccloud\u201d name stuck.<\/p>\n
The LMC and the SMC are something of a cozy pair and, from what I think I know (no guarantees here) they\u2019re gravitationally associated with each other. <\/p>\n
It\u2019s possible that the LMC and SMC are not of the same origins as the Milky Way but are, instead, travelers from somewhere distant. Whoa. That\u2019s spooky.<\/p>\n
Anyway, I\u2019ll finally get to the point here. The Monthly Notices of the Royal Astronomical Society, February, 2019, issue contains an article: \u201cThe aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud.\u201d<\/p>\n
The LMC is, right now, actually heading away from the Milky Way, but this is expected to change in a billion years when the LMC will boomerang and then home-in on our mother galaxy.<\/p>\n
The article predicts that the smash-up will suck so much material into the Milky Way that the supermassive black hole at our galaxy\u2019s center will increase in mass by a factor of eight. <\/p>\n
As things stand now, the Milky Way is apparently a bit underweight in its belly. But when it gobbles up the LMC\u2019s mass the Milky Way will be have a more typical profile. <\/p>\n
With that idea in mind, the article notes: \u201cAt the end of this exceptional event, the MW (Milky Way) will become a true benchmark for spiral galaxies, at least temporarily.\u201d<\/p>\n
You did note that \u201ctemporarily,\u201d right? I sure did. I did because of something that freaks me out. <\/p>\n
Before I get to that freak out, though, let me mention the \u201cspiral galaxies\u201d reference that came before the \u201ctemporary\u201d reference. The \u201cspiral\u201d refers to the beautiful spiral shape (like a pinwheel) of the Milky Way galaxy. This shape must be scientifically inferred. It can\u2019t be directly observed, at least in total, any more than you can directly observe the appearance of your house when you\u2019re sitting within it. But the Milky Way inference is pretty reliable, and telescopes can see the structure of similarly-shaped galaxies. <\/p>\n
A spiral galaxy shape is breathtaking, every bit as striking as Saipan\u2019s coral lagoon. If you get a sense of pleasure living amidst the natural beauty of Saipan, then you can relate to the fact that many astronomy enthusiasts actually have the same sense of wonder about the appearance of our home galaxy. <\/p>\n
Hey, so far, so good, right? Well, yeah, but now we have to look at this \u201ctemporary\u201d reference. <\/p>\n
The LMC (which is about 163,000 light-years distant) isn\u2019t the only galaxy destined to smack into the Milky Way. There\u2019s another one in the works. It\u2019s called Andromeda galaxy.<\/p>\n
Andromeda is far more distant (2.4 million light-years) than the LMC. Andromeda is also far bigger. It is, in fact, more massive than the Milky Way itself. Like the Milky Way it has a very nice spiral structure. Well, temporarily, that is. That\u2019s because in about 4 billion or 5 billion years, long after the Milky Way has digested the LMC\u2019s punch, Andromeda and the Milky Way are going to smoosh together. The resulting galaxy is expected to become a big blob, known more formally as an \u201celliptical\u201d galaxy. The well-defined arms of our spiral shape will be merely a faded memory. Ditto for Andromeda. <\/p>\n
If you want to take it personally, I guess that notion is a little bit depressing. But that\u2019s not what freaks me out. No, what freaks me out is that when I look at Andromeda though binoculars or a telescope, where it\u2019s this hugely impressive presence, I recall that it\u2019s coming straight for us at a speed of 250,000 miles per hour. Sure, I know that it\u2019s so distant that it\u2019s no threat to any human (humans, and probably all life on Earth, will be long gone when the collision happens), but, well, in galaxies, as in artillery, incoming is incoming. Yikes!<\/p>\n
So, in galactic terms, the long term isn\u2019t looking so great. It\u2019s probably better to focus on things nearer to home and closer on the calendar. So let\u2019s ink that Magellan party for 2021, OK? We\u2019ll toast each other. We\u2019ll toast ol\u2019 Ferdinand. And then we\u2019ll toast our beloved Milky Way, which is destined to become a big-bellied cosmic blob.<\/p>\n","protected":false},"excerpt":{"rendered":"
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