Total lunar eclipse to meet 'supermoon'
bbc.co.uk
bbc.co.uk
It has no meaning other than near perigee, it's not like the difference in the apparent moon size is all that noticeable, and we don't say that ISS is a 'superstation' or a satellite in a Molniya orbit is a 'supersatellite' when near perigee.
* Lunar eclipses are very common. They happen at least every 2 years. Every decade or so, they happen 4 times in two years.
* The term "supermoon" is a painful over exaggeration, since the visible difference between it and the average moon is tiny.
So yeah, enjoy the eclipse, but in the end it's the media trying to make news. :)
* Supermoon lunar eclipses are uncommon. * The visible difference can be up to ~14%, and its significantly brighter too.
But viewing the moon on the horizon will get you a bigger apparent size difference, no supermoon needed.
>A simple way of demonstrating that the effect is an illusion is to hold a small object (say, 1/4 inch wide) at arm's length (25 inches) with one eye closed, positioning it next to the seemingly large Moon. When the Moon is higher in the sky, positioning the same object near the Moon reveals that there is no change in size.
Here's an example I shot two full moons ago: https://www.flickr.com/photos/aaronbrethorst/20189872605/in/...
The moon looks absolutely monstrous here, but, I expect that if I had measured it when it was high up in the sky, the actual apparent size wouldn't have been any different.
Let's coin 'superdupermoon' for the 1% case.
And ... so what? As http://science.nasa.gov/science-news/science-at-nasa/2011/16... points out:
> Okay, the Moon is 14% bigger than usual, but can you really tell the difference? It's tricky. There are no rulers floating in the sky to measure lunar diameters. Hanging high overhead with no reference points to provide a sense of scale, one full Moon can seem much like any other.
About once a year Jupiter is in opposition. Should we call that a "super Jupiter"?
Within 90% of perigee, yes.
> it happens for about 10% of all eclipses.
Hayley's comet is visible for 100% of its orbits. It's passing is still a rare event because it happens typically once in a lifetime. A supermoon lunar eclipse will happen maybe half a dozen times in yours. It's an uncommon event.
> And ... so what?
If you're not interested, you're not interested. I don't like the term supermoon either. But it's interesting to me that the difference is measurable. Photographing the full moon at perigee and apogee and measuring the difference is my kind of fun.
Again, remember that you were being a devil's advocate. My "so what?" comment was mean to highlight the weakness of your counter-argument. It's not actually significantly naked-eye brighter but requires instruments to measure. Now you've jumped to something outside of the role that you've assigned yourself, because you switched to talking about 'your kind of fun' and using instruments to help with your fun. That's a very different topic than what you started with.
Saying "X is an uncommon event" does not, on its own, justify or explain anything. There are millions of rare events every day. Should we celebrate when Jupiter is at perihelion? That's only once every 11.86 years. What about when Mars is in aphelion? 67P/Churyumov-Gerasimenko was at perihelion on 13 August 2015 - did you celebrate?
I was merely pointing out that NdGT comments, while factual, were not really on point. I could also have said, "So what...?"
My arguments against the term supermoon are: 1. It piques public interest and then fails to deliver. 2. We have proper terms for the events that are occuring and should be using those terms instead.
Certainly these are stronger arguments than "But it doesn't look any bigger!"
But you're trying to place my "devil's advocate" role in the wrong context. Clearly the frequency of lunar eclipses has nothing to do with the term supermoon.
> how does your parallel to Halley's comment provide any justification to your counter-argument?
I think the point was rather clear. You were trying to argue that supermoon eclipses were not uncommon because they occur for, on average, 10% of all eclipses, but that was not the right metric. The occurance of these events over time is the correct metric.
> It's not actually significantly naked-eye brighter but requires instruments to measure.
It is 33% brighter. I would be surprised if that isn't detectable by the human eye. It certainly looks brighter to me tonight.
You don't need serious instrumentation to measure the change in size. Hold a quarter up to it so it just blocks out the moon. Measure the distance between your eye and the quarter. Now do the same when the moon is at apogee.
If you want to get technical, I don't really understand why it matters whether the difference is naked-eye visible or requires instrumentation. The prefix super- doesn't require it.
> Should we celebrate when Jupiter is at perihelion?
Are we celebrating? Certainly we "celebrate" in the form of news articles and increased observation when Jupiter is at perihelion, and, as you note, this event occurs once every ~12 year–more frequently than perihelion-sygyzy of the moon, Earth, and the sun. Although I think if it coincided with an eclipse of Jupiter by the Earth we would probably be too busy panicking to celebrate.
But these comparisons to other astronomical bodies don't hold water. The Moon holds a different place in our collective consciousness than these other astronomical bodies. Ask someone to point out Jupiter and most people won't be able to do so. Ask them to point out the Moon and everyone will be able to do so.
Supermoon, superjupiter, super67P/Churyumov-Gerasimenko are not incorrect. Why does the moon get special treatment? Probably for the same reasons it often does.
That is, upon research I found that the term 'supermoon' comes from astrology, and isn't really used in astronomy.
For example, yesterday I saw a news coverage that discussed the relation between the lunar eclipse, the "supermoon" and the zodiac signs. (Do you know the zodiac signs are changing this night? Or it was yesterday? Anyway I think there are a few zodiac calendars with small differences at the borders.) Even if the zodiac thing makes the new more interesting, it's bad to mix it with the real scientific facts.
First, I don't see lies OR the science here -- I don't see anyone trying to imply that this is scientifically meaningful, I just see people enjoying a group event of looking at the moon. I suppose I am not sure why it is on Hacker News, though. It's fun, and it is related to intellectual curiosities, but it is not an intellectual curiosity itself.
And second, when you say "even to make something more interesting to the people", it makes me think we have a different perspective on the cause here. I'm not advocating pushing a supermoon agenda in the name of getting people interested. I'm observing that people are interested in this event and choosing not to shit on their parade.
If they start telling me to make life decisions based on the supermoon or any other astrology, that is another matter. I do have a different opinion about the mercury retrograde events, for example -- those I see framed entirely in astrological terms by people who are not using the opportunity to look up or share pictures, who don't even understand why apparent retrograde motion occurs. I don't think that's the same thing.
When I was in school we had to learn the organs of the body, the parts of a cell, and other seemingly arbitrary terms. This comes from an old tradition where "science" was roughly equivalent to "knowing names."
I also grew up in an area where evolution was a contentious topic. The teacher only covered it for one day. But it's evolution which tied together the individual fields of 'botany' and 'anatomy' and 'bacteriology' into 'biology.' Evolution is what makes Rutherford's views wrong.
Words like "supermoon" and also "blue moon" fall into that category of meaningless terms that sound scientific but are little more than numerology, and not backed by any deeper meaning.
I have no problems getting together for a 'fun celebratory event'. I celebrate on New Year's eve like many others. I've been at fun celebratory events for meteor showers, and for other eclipses.
What I have problems with is justifying it with essentially an arbitrary and meaningless definition. Why is a "supermoon" at the 90% size threshold? Why not 95% Or 99%? By comparison, the New Year is also arbitrary, but not meaningless, as the history of the calendar shows.
To directly address the grandparent, there's nothing wrong with a fun celebratory event, but that's not what this is. If we could somehow turn it into one while retaining the term, I'd be fine with that.
It's Mercury retrograde, and it's time to celebrate math and science and reflect on the past! Long ago, humans looked up and it was pretty obvious everything revolved around the Earth. But then a few things go backwards at regular intervals, what's up with that? Explained by gods, by platonic solids, by complicated cosmic gears, it was a long standing puzzle. But after much puzzling, there was a realization that everything is much simpler and makes more sense if the sun is the center of the solar system, leading to the predictive physics that drives technology today! Quite the revolution -- and that's no accidental pun, it's the origin of this secondary meaning of the word "revolution".
How inspiring -- let's not let this inspiration go to waste, let's use it to reflect on our past relationships in our own lives, to revisit our past conclusions and see them in a new light, to have compassion for our past selves who had not yet not acquired the knowledge we have now.
And while we're at it, let's celebrate the discovery that gravity is a force that drops off extremely fast -- proportional to the square of the distance between two objects. Great news for us, because it means there is less gravitational attraction between me and Mercury when Mercury is closest than there is between me and the person sitting next to me, giving me plenty of opportunity to look at Mercury and be affected only by its light and the thoughts it inspires in me rather than hurled out of the solar system or into the Sun.
Similarly, there's an intrinsic difference between a 'nova' and a 'supernova'.
But if you look at 'supermoon', all you get is a number pulled out of a hat.
> I think that's in the same category as choosing to look at the moon together and feel a sense of awe.
Does the awe really come from someone telling you the moon is near perigee? Or from other aspects?
It's a temporal coincidence that the perigee moon now is near the full moon. In another decade, the perigee moon will be around the new moon. Will we be having the same coverage of the topic then? I doubt it.
Perhaps an analogy might help. People choose to believe in a 'Saturn return'. But 'Saturn return' for arbitrary reasons includes the time +/- a couple of Earth years around a full Saturn year. I can still express my dislike for the term and concept even if you are in awe to know that you are one, or two, or even three Saturn years old.
In those images the moon is bigger than my fist, and all the features are very clear even though it's a full moon.
> Does the awe really come from someone telling you the moon is near perigee? Or from other aspects?
Oh, not from that information, no. It comes from going out and looking at the moon, taking pictures, and looking at all the pictures that populate my facebook feed.
The "super moon" to me is from last quarter to new moon when it's out of the way and not flooding the sky with its unwanted brightness so I can see the deep sky :)