Tag: tides

Bad Astronomy review: Terra Nova

By Phil Plait | October 17, 2011 6:30 am

So I finally watched the pilot episodes of the new Fox scifi drama "Terra Nova" (it airs Mondays at 8:00 p.m. ET). I found it watchable, with some potential, and like every other TV show in existence (except "Firefly") it had some things I liked and some I didn’t. I got email about it due to a couple of lines in the pilot, which I’ll get to in a sec. First, a quick overview.


Gotta get back in time

The idea behind the show (no real spoilers here, since this is all explained in the first minute of the program) is that by the year 2149, the Earth is dying. Pollution, global warming, and so on have made the planet nearly uninhabitable. People need rebreathers just to go outside, and many scenes show huge chimneys pumping smoke into the air just to hammer home that point. Population control is mandatory; having more than two kids is an invitation for the police to come.

The show centers on a family – cop father, brilliant doctor mother, rebellious teenage son, science whiz-kid teenage daughter, and their youngest, a girl. And yeah, if you count three kids, good for you! That drives part of the plot in Part 1 of the show, so I won’t spoil it.

The big plot device in the show is that a fracture in time is discovered — how and why are not disclosed, perhaps to be revealed in a later episode — that goes to 85 million years in the past. People are being sent back in time to populate the still-clean planet, save humanity, fight dinosaurs, and so on.

I’ll note that I like how the time travel was handled. When we join the story, time travel has already been around a while — this family is sent back as part of the tenth wave of colonists — so the writers didn’t have to spend a lot of time talking about how it was done. It just is. Also, the writers circumvented the inevitable fan rage with a short expository scene stating how this isn’t really our past; the time line has split, so it doesn’t matter if you step on a butterfly or eat an entire herd of dinosaurs. It won’t change the future. That made me smile. Score one (pre-emptively) for the writers.

Of course, the show tried to distance itself from "Jurassic Park", and did so by having the first look at the dinosaurs be a herd of brachiosaurs, and then having the main characters in souped-up jeeps getting chased by a carnivorous velociraptor/T-Rex-like animal.

Um, yeah. Oops.

I’m no paleontologist, and I like watching dinosaurs with big sharp teeth eat a person as much as the next guy, so that part was fine. But then they went a little bit out of their way to add some astronomy, and kinda blew it. So I have to jump in here a bit.

What follows is me nitpicking the science of a couple of lines of dialogue. I don’t do this to be petty — I gave up on that in my reviews a long time ago — but just to use these lines to point out the real science. Any snarking is incidental.

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Star eaten by a black hole: still blasting away

By Phil Plait | August 26, 2011 6:30 am

In late March of 2011, an extraordinary event occurred: a black hole in a distant galaxy tore apart and ate a whole star (I wrote about this twice at the time; here’s the original post, and a followup article including a Hubble image of the event).

Now, there’s more info: the black hole, lying at the center of a galaxy nearly 4 billion light years away, has about 8 million times the mass of the Sun. When it tore the star apart, about half the mass of the star swirled around the black hole, forming twin beams of matter and energy that blasted outward at a large fraction of the speed of light. The folks at NASA’s Goddard Space Flight Center made a great animation to show this:

The star was ripped apart by tides. The thing about black holes is, they’re small: this one was probably about 15 million kilometers across. A typical star is about a million km across (the Sun is 1.4 million kilometers in diameter, for comparison). This means the star could get really close to the black hole, and that’s why it was doomed. The force of gravity drops with distance, so as the star approached, the side of it facing the black hole felt a far greater force than the size facing away. That stretched the star, and the stretching increased as the star got closer. At some point, the force was so great it exceeded the star’s own gravity, and it could no longer hold on to its material. The black hole won — as they usually do.

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CATEGORIZED UNDER: Astronomy, Cool stuff, Top Post

Followup on the star torn apart by a black hole: Hubble picture

By Phil Plait | April 7, 2011 8:31 am

I recently wrote about a mind-boggling event: astronomers capturing what are apparently the final moments in a star’s life as it was literally torn apart by a black hole.

Today, NASA has released some new pictures of the event, including this Hubble Space Telescope shot:

[Click to embiggen.]

I know, it may not look like much at first. But remember what you’re seeing: the violent death of a star ripped apart by the gravity of a black hole… and it’s happening 3.8 billion light years away! That’s about 40,000,000,000,000,000,000,000 kilometers, so the fact that we can see it at all is pretty amazing. And terrifying.

In this false-color Hubble image, the galaxy and explosion are marked. Pretty much everything you see in the picture is a distant galaxy, a billion of more light years away. Normally, the host galaxy itself would appear as a dot, at best with some small amount of fuzz around it, the glow of billions of stars reduced by the incredible distance. But the dying light of the star increased the galaxy’s brightness by a lot. A whole lot.

This image (click to greatly embiggen!) is a combination of visible light (white), ultraviolet (purple), and X-rays (yellow and red) from NASA’s Swift observatory, the satellite that first detected the explosion. While the spikes are not real — they’re just an optical effect from the telescope itself — it still speaks to the drama of what we’re seeing.

And so just what are we seeing?
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CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

No, the "supermoon" didn't cause the Japanese earthquake

By Phil Plait | March 11, 2011 10:02 am

[UPDATE: I have posted an article with more info on the earthquake and where you can donate money toward the relief efforts.]

Japan suffered a massive earthquake last night, measuring nearly magnitude 9. This is one of the largest quakes in its history, causing widespread and severe damage. Before I say anything else, I’m greatly saddened by the loss of life in Japan, and I’ll be donating to disaster relief organizations to help them get in there and do what they can to give aid to those in need.

While there isn’t much I can do to directly help the situation in Japan, I do hope I can help mitigate the panic and worry that can happen due to people blaming this earthquake on the so-called "supermoon" — a date when the Moon is especially close to the Earth at the same time it’s full. So let me be extremely clear:

Despite what a lot of people are saying, there is no way this earthquake was caused by the Moon.

The idea of the Moon affecting us on Earth isn’t total nonsense, but it cannot be behind this earthquake, and almost certainly won’t have any actual, measurable effect on us on March 19, when the full Moon is at its closest.

So, how can I be so sure?

The gravity of the situation

Here’s the deal. The Moon orbits the Earth in an ellipse, so sometimes it’s closer to us and sometimes farther away. At perigee (closest point) it can be as close as 354,000 km (220,000 miles). At apogee, it can be as far as 410,000 km (254,000 miles). Since the Moon orbits the Earth every month or so, it goes between these two extremes every two weeks. So if, say, it’s at apogee on the first of the month, it’ll be at perigee in the middle of the month, two weeks later.

The strength of gravity depends on distance, so the gravitational effects of the Moon on the Earth are strongest at perigee.

However, the Moon is nowhere near perigee right now!

The Moon was at apogee on March 6, and will be at perigee on March 19. When the earthquake in Japan hit last night, the Moon was about 400,000 km (240,000 miles) away. So not only was it not at its closest point, it was actually farther away than it usually is on average.

So again, this earthquake in Japan had nothing to do with the Moon.

Time and tide

So why would people think this is due to the Moon?
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CATEGORIZED UNDER: Antiscience, Astronomy, Debunking

Bill O'Reilly: tidal bore

By Phil Plait | January 31, 2011 11:09 am

Look, I know. Bill O’Reilly is a far-right ideologue who couldn’t grasp reality with a hundred meters of velcro and a ton of Crazy glue. He’s mean-spirited, loud, and wrong, wrong, wrong. Debunking him is like debunking the Tooth Fairy; so easy and obvious that it’s almost mean on my part to do it.

Yet here we are.

By now the entire planet has heard O’Reilly’s bizarre litany about tides, and how he claims they prove the existence of God. As he has said on many an occasion, "tide goes in, tide goes out, never a miscommunication." By this he means that the harmony of nature, the amazing interconnection between things, clearly argues for God.

The problem is, he’s wrong. Twice, actually. First because he’s making the "God of the Gaps" fallacy: if something can’t be explained, then God must have done it. That’s pretty silly, since of course the far more likely explanation is simply that O’Reilly can’t explain it. That doesn’t mean I can’t! And in the case of tides, I can explain them, as can my friend Neil Tyson, and pretty much every other astronomer on Earth.

The thing is, either O’Reilly cannot learn, or he hopes his audience won’t. Because on his YouTube channel — yes, O’Reilly has a YouTube channel, I believe that’s the Second Horseman of the Apocalypse — he not only makes this same claim again, he digs himself deeper:
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ANOTHER insanely awesome shot of the solar eclipse?!

By Phil Plait | January 8, 2011 7:00 am

Y’know, I should never deal in superlatives. I said Thierry Legault’s shot of the ISS during the solar eclipse last week was the best picture of it, but now, as amazing as that picture is, I think we’ve found something to tie it: the Japanese solar observing satellite Hinode took this jaw-dropping video:

OK, I’ll say it: Holy Haleakala!

Hinode (pronounced HEEN-oh-day, which I’m telling you because I always say HI-node in my head when I see it) orbits the Earth, and has a near-continuous view of the Sun. When the Moon slipped between us and our star on January 4, Hinode had what might have been the best view. This video was made using images from the X-Ray Telescope, or XRT, and is sensitive to objects at temperatures of millions of degrees — the Sun’s magnetic field routinely generates such energies. You can see the looping material on the Sun, following the arcing lines of magnetism. The Moon is dark at these wavelengths, so it appears black in the video.

The other cool thing is the size difference between the Sun and the Moon. The Sun is roughly 400x bigger than the Moon and 400x farther away, so they look about the same size in the sky. But the Moon orbits the Earth in an ellipse, and can change its distance to us by quite a bit, well over 10% — that means its apparent diameter as seen on Earth can change by 10% too.

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CATEGORIZED UNDER: Astronomy, Cool stuff
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