Why Comet Elenin is Not A Brown Dwarf Star

It's nothing new for people to be frightened by a comet. Humanity has been afraid of them ever since we evolved a neck and used it to look into the night sky. Comets seem frightening to us because they represent something unfamiliar in an otherwise very familiar sight: the heavens.

So I suppose it's not so strange that a small, relatively meager comet is causing a ruckus. True to our ancient roots, many are associating this comets' arrival with dread and trepidation. Many think it is causing earthquakes - most notably the one in Japan - and that it is even masquerading or somehow hiding a brown dwarf star that is heading dangerously close to us.

The name of the comet is Elenin and boy are people afraid of it. Fear is a crippling thing, the first thing to go of course is any semblance of rationality and clear thinking. In addition to causing death and destruction in the form of earthquakes, there are those who think even stranger things.

One claim in particular - that comet Elenin is a brown dwarf star - I find particularly bizarre, and while I probably should just ignore it, for some reason, I can't bring myself to do that. The only way someone could even make that connection is if they really have no idea about what a comet or a brown dwarf star actually is.

In my opinion, thinking like this usually results from a simple lack of education on the subject. If people know what a brown dwarf actually is, they wouldn't mistake it for a comet.

Once more, like I did with my analysis of how comet Elenin could never have caused the Japanese earthquake in March of 2011, I'm going to look at this claim and give you an analysis of why Comet Elenin cannot - IN ANY WAY - be considered a brown dwarf star.

Nor, once you see the difference, can it hide one.

Let's begin by looking at each celestial body in turn: let's first look at what a comet is, then a brown dwarf star. I think once you learn the difference, you would find it amazing that anyone can ever think one could be mistaken for the other.

What is a comet?

Comets are made from the garbage leftover from the formation of the solar system. Whatever atoms did not end up either as part of the Sun or a planet collected out in the boondocks of our Solar System, known as the Oort Cloud.

Over time, these atoms collected into larger chucks of ice and rocks and quietly orbit out in the boondocks.

Every once is a while though, one of these chunks will get a gravitational kick that sends it out of this quiet, lonely orbit. Many times this kick will send it flying out of our solar system, away from the Sun, never to be seen or heard from again.

At other times, it will fall the other way, towards the Sun.

Since comets range in size from a small boulder to larger than a mountain, as they fall closer to the Sun, the loose bits of dust and ice that make up the comet begins to heat up and then gets blown back by the solar wind. This is what creates the tail of a comet and it becomes larger and more pronounced as it approaches its flyby around the Sun.

How big the tail gets depends on how big the comet is and how close it gets to the Sun when it comes around.

And they live in a bad neighborhood.

So let's take a look at Comet Elenin.

Comet Elenin is small, dim and kinda boring as comets go.

It is a long period comet originating from the outer edges of our solar system. Its mass is smaller than average and its trajectory will take it within orbit of Earth as it circles the Sun. It will make its closest approach on October 16th where it will come no closer than 21 million miles.

That is more than 84 times the distance of the Moon from the Earth.

Measurements of the comet put it at about 2 to 3 miles wide and most estimates state that we're going to need a pair of binoculars at least to be able to see this when it passes by.

A lot of people worry that it will pass between the sun and the earth when it comes by blocking out the sun and causing all sorts of problems. Elenin is not going to do that, it can't pass between us. Even if it did, there would be no effect. Elenin is only 2 miles wide, the sun is 865,000 miles wide, the effect would be similar to a speck of dust passing in front of a stadium light.

Or a fruit fly passing in front of an elephant walrus. Hmm, I guess there are times when that can work.

What is a brown dwarf?

Brown dwarfs are something else entirely and can be described in one word: Jupiter.

While Jupiter is often called the largest planet in our solar system, it's a 'gas giant' and as such resides in a kind of an astronomical nomenclature grey area.

Jupiter is a collection of gas, mostly hydrogen and helium that wasn't massive enough to start those gases fusing. Since stars are defined by both their mass and luminosity, by those characteristics, Jupiter isn't quite a star - it doesn't fuse anything (at least not that we know of) and it isn't very luminous.

Jupiter does radiate though. It gives off more energy than it receives from the Sun, so it is more of a glowing planet.

Brown dwarfs are often characterized by astronomers as 'failed stars'. These are bodies that simply didn't get massive enough to ignite nuclear fusion.

Sound familiar? Those were the same words used to describe Jupiter.

In fact, Jupiter-sized planets are on the low-end of the mass scale for brown dwarf stars. Brown dwarfs range in size from slightly smaller than Jupiter to around 80 times that of Jupiter.

A star greater than 80 Jupiter masses is large enough for deuterium fusion to begin, so a body that size starts to look more like an actual star.

Now you can begin to see the grey area, Jupiter actually qualifies both as a gas giant planet and a brown dwarf star.

OK, based on this background information, we can start to look more closely at the claim that Comet Elenin is not a comet, rather it's a brown dwarf star heading startlingly close to Earth.

Why Comet Elenin Cannot Be A Brown Dwarf

The first evidence refuting the idea that Comet Elenin is a brown dwarf is that we've actually observed Elenin. We've seen it with telescopes on the ground and in space.

In the middle of August 2011, the orbit of Elenin was such that it could be seen by STEREO-A which is one of a pair of space telescopes observing the Sun.

Everyday for a couple of weeks, STEREO-A observed Comet Elenin until it travelled into range of another solar satellite, SOHO.

What did the observations tell us? Not surprisingly, it looks just like a comet. It is the size of a comet. It is made up of dust, gas and ice. Its trajectory indicates that it came from the Oort cloud. It has a coma and a tail.

The exact mass of Elenin hasn't been published as I write this, but what is known is that as comets go, this one is dim and smaller than most. As it passes by Earth on October 16, 2011 at a whopping 21 million miles distant.

There is no chance this comet is going to hit the Earth.

Given that there are indisputable observations pointing to this being a comet, how can this be mistaken for a brown dwarf star?

In what way is this small, dim cosmic gas ball anything like, oh, I dunno, JUPITER?

The mass of Jupiter is roughly 1.8986 x 10²⁷ kg, that 317 times bigger than the Earth.

Let's give Comet Elenin the benefit of the doubt and say that it has the mass of an average comet, it doesn't, but let's say it does. That would make it 4 x 10¹⁴ kg or 15 million times smaller than the Earth.

Here's the math: number of times smaller Elenin is than Earth = mass of Earth / mass of Elenin = 5.9742 x 10 ²⁴ kg / 4 x 10¹⁴ kg = 14,935,500,000 (I rounded up). And Jupiter is 317 times bigger than Earth.

Conclusion

So the claim is that Comet Elenin is a failed, or brown dwarf star, instead of a comet. I've even heard it said that the observations were messed up and we made a mistake in classifying this as a comet.

But brown dwarf stars are pretty unmistakable objects. Things the size of Jupiter (or larger) roaming the solar system are pretty hard to miss.

Right now, as I write this, Jupiter is high in the evening sky around midnight. In fact, it's the brightest point of light over my head (aside from the frackin' used car lot down the road).

If it's that bright when it's 500 million miles away, how bright would Elenin be if it was a brown dwarf? Elenin is currently less than 85 million miles away. That's six times closer to us than Jupiter. Can you imagine how bright that would appear in our sky if that were the case?

Well you don't need to, lets do the math. Luminosity falls off as the square of the distance. If, at 500 million miles, Jupiter has an average apparent magnitude of -2.6 (I'm not going to explain the magnitude scale, it's just a number for our purposes).

Using the formula for magnitudes, at 0.234 au (21 million miles) Jupiter would appear at magnitude -11, at Elenin's closest approach to the Earth.

If Elenin were in fact a brown dwarf, it would be (at it's dimmest) at least as bright as Jupiter. Remember that Jupiter is at the small end of the scale for these bodies. If a jupiter-sized object were going to get that close, it would be extremely bright.

I promise you, we would notice that.

So, setting aside for a minute that everything we see when we look at Comet Elenin points to it being a comet: it has a comet's trajectory; it has a tail; it's made of what comets are made of; and it is the size of a comet, the object orbiting the Sun in that spot cannot be a brown dwarf Star.

I think my chain's being yanked

Sometimes these claims are so outrageous that I'm starting to think that the people who make them don't really believe them either. I think they're just yanking my chain, you know, sort of like the guys who disagree just to disagree?

I think it's fun for some people to just start making wild claims to see what happens. It's worked for many people before, like the 'Face on Mars' guy Rickard Hoagland, he managed to get lots of attention and speaking engagements by making wild claims.

It's just easier to get attention this way. The problem is of course, that they only get that attention because people are too uneducated and simply don't know better.

The only way people like that can get any attention at all is if people take them seriously. Those that give it to them generally know very little about the night sky.

Sooooo, people like me get their panties in a bunch and start yelling as loud as they can about how and why whatever-wild-claim-is-made is all crap.

I've fallen into the trap: they have me. And more attention.

I seem to be writing more debunking articles than I'd like lately. I hope I'm wrong about people's intentions here, like I said, it's human nature to be afraid of comets.