Blogs / Bad Astronomy

How far away are things?

That is perhaps the most basic question in astronomy, and in some ways the most aggravating. For nearby stuff — and by that I mean everything from the Moon out to stars about 1000 light years away — we can measure distances directly. Bouncing radar pulses off of planets gives us their distance, and in some cases we’ve sent probes to them so their distances are extremely well known. For nearby stars we can use parallax, which is using the motion of the Earth around the Sun to see how that affects how we see the position of the stars in the sky.

But for distant galaxies, getting their 10-20 is a lot harder. That’s why objects like the spiral galaxy NGC 3021 are so useful:

Hubble’s view of NGC 3021. Click to get to much more cromulently embiggened images. Both images credit: NASA, ESA, and A. Riess (STScI/JHU)

OOoo. Ahhhhhh.

That pretty li’l thing is a cosmic bootstrap device. It and other galaxies like it have been under the scrutiny of my old friend Adam Riess, who has some big questions for them. Like, how fast is the Universe expanding?

And NGC 3021 may just have the answer.

That particular galaxy has two extremely useful properties. One is that it contains a type of variable star called a Cepheid variable, which are stars that literally pulsate in size and brightness. The time it takes to change in brightness is directly related to its absolute brightness: the more luminous the star is, the longer it takes to pulse. If you measure its precise pulse period, you find the star’s true brightness. Compare that to how bright it appears in a telescope, and voila! You get the distance.

Cepheids in NGC 3021.

Cepheid measurements yield pretty good distances for nearby galaxies, but after a certain distance they are too faint to see. We need a better rung on this distance ladder… and we have one. Supernovae.

Type I supernovae are a kind of exploding star that we think (well, we’re actually pretty sure) all explode in such a way that their absolute brightness can be determined, so, like Cepheids, their true distance can be found. And we can see them out for hundreds of millions of light years, which is really really far away. This makes them incredibly powerful beacons for astronomers.

The cool thing is, NGC 3021 and others like it have Cepheids in them, and are also known to have hosted Type 1 supernovae! Over ten years ago, a Type I went off in NGC 3021, and very precise measurements of it were made, including how far away it was. So for galaxies like NGC 3021 we have two methods of measuring distances which can be tied together in a single galaxy that can be observed with a single telescope, like Hubble. That means that uncertainties in the distance measurements using the two systems can be hammered away, and we get more reliable measurements.

And since we can see supernovae out to such fantastic distances, that means we can accurately measure the expansion of the Universe. Using supernovae to measure the distances of remote galaxies can be compared to the distances we get for those using the redshift, the Doppler-like shift in the starlight coming from those galaxies. So again, we’re tying together different ways of measuring distances, allowing us to refine just how this old cosmos of ours is, and how quickly it’s expanding.

Adam Riess and his team observed quite a few galaxies in this way, and figured just how fast the Universe is growing to unprecedented accuracy. His result: 74.2 ±3.6 kilometers/second/megaparsec. That means for every megaparsec (about 3 million light years) you go out, the Universe is expanding 74.2 km/sec faster. So a galaxy 10 Mpc away would be moving away from us at 742 km/sec. Adam’s measurement jibes well with other measurements, so there is reason to be confident in his results.

By knowing this number accurately, all we have to do is measure how fast the galaxy is moving away from us — a very easy measurement to make — and we can find its distance. Of course, it’s more complicated than that, but that’s the basic idea.

But by nailing down all these numbers, we can in turn nail down such things as how much dark energy is in the Universe, and maybe even rule out some theories as to what this mysterious stuff is. It’s pushing on the fabric of space and time, making the Universe swell faster every second of every day, and we have no clue what it really is. Well, that’s unfair: we have lots of clues, but we don’t know what’s causing it. Observations of NGC 3021 and other galaxies like it will help us unravel some of these mysteries, which are among the biggest in science today.

Who would have thought that all this could happen just by figuring out how bright some stars are?

Oh yeah, scientists did. That’s what they do.

In January, I had the distinct pleasure in hosting a panel in Pasadena called The Mysteries of the Cosmos. It featured four brilliant astronomers discussing their quest to understand the Universe. It was hosted by several groups, including Discover Magazine. The whole thing was filmed, and DM now has the videos online. Here’s Part 1.

The others are on that link above. I had a fantastic time, and I hope you enjoy watching these videos. Honestly, being on stage with Debra, Andrea, Saul, and Mike was such an honor, and listening to them talk about these astronomical topics has made me feel a whole lot better after what’s been a really rough week on this blog. Sometimes, it’s good to remember that there are questions — and answers — much bigger than ourselves.

Reading through the truly awful antivax responses to my post where I state flatly and with conviction and evidence that the antivax movement is killing people, I was stunned to see Toni McCaffery had posted a response as well. Ms. McCaffery is the mother of Dana, the infant who died recently from whooping cough because the vaccination rate in NSW Australia is too low to afford herd immunity.

Toni: if you read this, please know that my heart goes out to you, and I swear to you that the bloggers on the right side of this issue will not rest, and we will continue to fight this fight as long as we can. It’s the least we can do for you, and for Dana.

A Facebook page has been created in Dana’s memory, and a website has been started as well to help get Australians to immunize their children.

I think that all of you reading this might also enjoy these four items that show you that we can help.

1) GiveVaccines.org will donate toward vaccinations for every trivia question you answer correctly. In a few minutes I was up to 30 correct answers.

2) Here’s a terrific post from an astronomer who vaccinated his son. It’s in Spanish, but there’s a link there to translate it.

3) Orac takes on Huffington Post, and annihilates them in stark detail.

4) But of all of these, this might be my favorite: an antivax mom comes around and becomes provax for all the right reasons. That’s a great story and really made my day.

We’re facing a huge and growing problem, but we have to continue to fight. Lives are at stake, the most innocent lives of all. Keep fighting, keep being heard, and keep spreading the word.

I don’t know what’s worse: people who really think they are seeing skulls on Mars, or people in the media who think this is honestly worth reporting.

C’mon, The Telegraph: srsly? This is news?

I wonder if it’s any better than MSNBC posting a picture of two Mexican wrestlers staring at a griddle they think has the Virgin Mary on it.

Yes, you read that correctly.

Skeptics. Our work will never be done.

And, of course:

Tip o’ the Rorschach blotter to BABloggees Spencer Cunningham and Vernon Balbert.

Kiki Sanford is a neurophysiologist, a webceleb, a Skeptologist, and a pretty cool chick (haha: she studies birds. Haha). I’ve known her for a while now (though we only met IRL last year) and was impressed enough with her to invite her to come to the Conference on World Affairs here in Boulder a few weeks ago.

While she was here she interviewed another fave of mine: Michelle Thaller, a space scientist who also loves to talk science to the public. It’s a good brief interview, and worth your time.

Kiki also now has a live web show called Dr. Kiki’s Science Hour with Leo Laporte. There’s a chat room with tons of folks in it, and this week’s show had novelist (and yet another BA tweep) Scott Sigler. I have friends everywhere. Anyway, it was very entertaining, and it’s now available as a podcast. And hey, at 1:04:30 I get a shout-out!

The show runs live every week on Thursday at 18:00 Eastern time (22:00 GMT). Check it out!

During the Texas State Board of Education hearings on science standards for Texas schoolchildren, BoE member and staunch creationist Barbara Cargill decided that the age of the Universe was up for vote. Oddly enough, I had some issue with that. You may vote on issues all you want, and you can even vote on morality if you’d like, but scientific reality is not a matter of opinion and cares not for the majority vote.

The National Center for Science Education has video of the moment where it becomes clear that Ms. Cargill, not happy enough to destroy biology for students, proposes an amendment to creationize astronomy as well:

Listening to her gives me the heebie-jeebies. About the astronomy standards, she says "…there are different estimates [of the age of the Universe]… they will be taught about 12 - 14 billion years ago, but this leaves it open a little bit to discuss how many billions."

It is absolutely clear from what she is saying that she is deliberately trying to weaken the teaching of the old age of the Universe. Another member queries her specifically, asking if this will open up astronomy to the teaching of literal Biblical creationism. Cargill then completely dodges the question, saying she is simply taking the language of the recommendations. But that language is clearly saying the Universe is old, and there is a small amount of uncertainty (actually, only about 120 million years) in the age estimate of the Universe.

What she did, to put it simply, is a crock. It is perfectly transparent what she wanted: to wedge open the door to allow the teaching of young-Earth creationism in the classroom, using the standard "strengths and weaknesses" creationist propaganda tactic.

Need I say it? Her amendment passed, 11 to 3.

I honestly feel bad for any child entering the Texas public school system over the next ten years, and I sincerely hope that the Legislature of the Lone Star State is able to take away the ridiculous amount of power the BoE has. They are flaunting their violation of the First Amendment of the Constitution of the United State of America (not to mention bending or breaking that pesky "false witness" Commandment), and their influence reaches well beyond their own state borders.

Tip o’ the ten gallon hat to BABLoggee Javier Pazos for alerting me to the video.

Posted without comment.

Tip o’ the VISOR to Gordie Lachance.