[dalke]

Is there anyone besides me who deeply dislikes the term 'supermoon'?

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.

[furyofantares]

Maybe not a useful term for science but what's wrong with a fun celebratory event? The general population isn't interested enough to tolerate news stories about every full moon but they aren't so uninterested as to want zero coverage. If people want to be reminded to go out and look up every once in a while and have a minor social event on the Internet where people are looking at and sharing photos and articles with friends and strangers from all over the world, supermoons and lunar eclipses happen at a frequency that's pretty good for that, and why not have a fun name as well?

[gus_massa]

I don't think it's good to mix science and lies, even to make something more interesting to the people. Science tries to distil the true, it's not easy, it's full of error, it's full of egos and scientific politics, ..., but if the objective is not the true it's not longer science.

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.

[furyofantares]

I think I see two differences in perspective that may be leading to communication errors.

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.

[dalke]

There's a quote attributed to Rutherford that “In science there is only physics; everything else is stamp collecting.” (See http://www.quotationspage.com/quote/26219.html for a citation.)

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.

[furyofantares]

I don't understand your last comment. I agree that the New Year is arbitrary, but years themselves are quite meaningful and useful. But I don't think the New Year celebration has anything to do with celebrating the concept and understanding of a year. We have added extra non-scientific meaning to it by using it as cultural event of reflection on the past and planning for the future. I think that's in the same category as choosing to look at the moon together and feel a sense of awe.

[dalke]

I'll try again. I'm not concerned about the arbitrariness of the term 'supermoon'. I dislike the meaningless of it. A good term has meaning behind it. The choice of the new year is arbitrary, and has changed over the centuries. We can examine why there is a calendar system, and compare sun-based to moon-based calendar systems. We can understand that the turnover point of the Gregorian or Mayan calendar is arbitrary, and for the more recent calendar systems we know some of the reasons for why they exist.

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.

[furyofantares]

Thanks, I understand what you mean about the term itself not conveying information now.

> 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.

[DanBC]

The other problem with the supermoon term is the ridiculous images used to illustrate the articles about supermoons.

In those images the moon is bigger than my fist, and all the features are very clear even though it's a full moon.

[mikeash]

It's no coincidence that the people I see making a big deal about "supermoon" and that are also the people talking about crossing the galactic plane, how you need to be prepared for emotional problems as Mercury goes retrograde, and similar nonsense.

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.

[furyofantares]

Maybe we should just start celebrating Mercury retrograde ourselves.

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.

[hugh4]

Yes, but people are inevitably disappointed by the "Supermoon", which isn't really noticeably larger or brighter than it would be at any other time. If you woke up from a coma and looked at the moon, would you be able to tell if it were super- or not?

[DanBC]

But people would be better if the moon isn't full. You get to see more on the moon, and you get to see more in the rest of the sky.

[sixbrx]

This is a good point, for those who might be interested enough by the hoopla to be trying to see it through someone's telescope. Full moon is the worst time to view the moon through a telescope. Everything is washed out and lacks shadows that give the terrain a 3-D perspective.

[FlyingAvatar]

I saw Neil deGrasse Tyson "on tour" on Thursday, and this was one of his rants in his presentation:

* 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. :)

[cgriswald]

To play devil's advocate:

* 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.

[dalke]

I believe the definition of 'supermoon' is 'closer than 90% of the time", so yes, it happens for about 10% of all eclipses.

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"?

[cgriswald]

> I believe the definition of 'supermoon' is 'closer than 90% of the time"

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.

[dalke]

In your position as devil's advocate, how does your parallel to Halley's comment provide any justification to your counter-argument? We don't have a special term for a comet when it's within 10% of perihelion.

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?

[cgriswald]

> In your position as devil's advocate, how does your parallel to Halley's comment provide any justification to your counter-argument?

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.

[rev_bird]

Clearly that would be a Supiter

[jsprogrammer]

Do objects really get a larger apparent size at the horizon? I guess there might be a small magnification effect from the additional atmosphere and angle?

[aaronbrethorst]

I assume it's the result of our brains being better able to make a size comparison when the moon is at the horizon.

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.

[ezequiel-garzon]

Possible explanations have only appeared in recent years. It looks like by trying to make an adjustment your brain gives you a distorted image. Truly amazing.

https://en.wikipedia.org/wiki/Moon_illusion

[jsprogrammer]

Ah, so as I thought. There is no difference in apparent size.

>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.

[cgriswald]

Yes. Not just the moon, but constellations as well. Maybe other things. There's no consensus on why. Refraction is one idea. Another is its the way our brains process the information from our eyes.

[jsprogrammer]

Brain processing shouldn't affect apparent size. Apparent size can be measured easily. I'd guess the difference in apparent size between something at zenith and on the horizon is less than a percent.

[cgriswald]

Sorry, I meant how it appears to you, not it's apparent size.

[jsprogrammer]

I've been getting the moon in perfect view from my kitchen window for the last several evenings. It gets great framing from the treelines on the local hills and the walls of nearby buildings. I think the framing helps you to focus on the moon (it's relatively bright compared to the rest of the scene) and appreciate the detail (some of which you can actually see with decent human vision). You are also seeing it right next to objects that you have more familiarity with their size, which helps you to appreciate the scale of the object.

[Mz]

Maybe you mean total eclipses? Because lunar eclipses happen two to three times every single year, always paired with a solar eclipse (two weeks apart). Most of them are partial eclipses.

[alexkadis]

I'm just happy that astronomy is making the news

[dalke]

Are you sure it's not astrology making the news?

That is, upon research I found that the term 'supermoon' comes from astrology, and isn't really used in astronomy.

[xefer]

I hate the term also. It just seems like a product of superlative-driven headline click bait that has infected everything.

[sixbrx]

It is a bit of an exaggerated term, it raises expectations to a point that it can't really meet.

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 :)

[TaylorSwift]

I like supermoon. It sounds tasty.