The Milky Way is twice the size we thought it was

[qdave]

It took just a couple of hours using data available on the internet for University of Sydney scientists to discover that the Milky Way is twice as wide as previously thought.

Astrophysicist Professor Bryan Gaensler led a team that has found that our galaxy - a flattened spiral about 100,000 light years across - is 12,000 light years thick, not the 6,000 light years that had been previously thought.

Proving not all science requires big, expensive apparatus, Professor Gaensler and colleagues, Dr Greg Madsen, Dr Shami Chatterjee and PhD student Ann Mao, downloaded data from the internet and analysed it in a spreadsheet.

"We were tossing around ideas about the size of the Galaxy, and thought we had better check the standard numbers that everyone uses. It took us just a few hours to calculate this for ourselves. We thought we had to be wrong, so we checked and rechecked and couldn't find any mistakes."

The University of Sydney team's analysis differs from previous calculations because they were more discerning with their data selection. "We used data from pulsars: stars that flash with a regular pulse," Professor Gaensler explains. "As light from these pulsars travels to us, it interacts with electrons scattered between the stars (the Warm Ionised Medium, or WIM), which slows the light down.

"In particular, the longer (redder) wavelengths of the pulse slow down more than the shorter (bluer) wavelengths, so by seeing how far the red lags behind the blue we can calculate how much WIM the pulse has travelled through.

"If you know the distance to the pulsar accurately, then you can work out how dense the WIM is and where it stops - in other words where the Galaxy's edge is.

"Of the thousands of pulsars known in and around our Galaxy, only about 60 have really well known distances. But to measure the thickness of the Milky Way we need to focus only on those that are sitting above or below the main part of the Galaxy; it turns out that pulsars embedded in the main disk of the Milky Way don't give us useful information."

Choosing only the pulsars well above or below us cuts the number of measurements by a factor of three, but it is precisely this rejection of data points that makes The University of Sydney's analysis different from previous work.

"Some colleagues have come up to me and have said 'That wrecks everything!'" says Professor Gaensler. "And others have said 'Ah! Now everything fits together!'"

The team's results were presented in January this year at the 211th meeting of the American Astronomical Society in Austin, Texas.

University of sydney

[TheElite]

How could people be calculating the wrong figure all this time?

[MGS4-SS]

How could people be calculating the wrong figure all this time?

The University of Sydney team's analysis differs from previous calculations because they were more discerning with their data selection. "We used data from pulsars: stars that flash with a regular pulse," Professor Gaensler explains. "As light from these pulsars travels to us, it interacts with electrons scattered between the stars (the Warm Ionised Medium, or WIM), which slows the light down.

[guru]

How could people be calculating the wrong figure all this time?

happens all the time. till someone comes along tries a new way or looks at the same thing from different angles. don't be surprised if this measurement of the Milky way diameter is changed again..

[vincent]

How could people be calculating the wrong figure all this time?

Science builds on doubt, not absolutes :sleep:

[TheElite]

Then there was doubt for quite a long time.

[vincent]

Then there was doubt for quite a long time.

There's always going to be doubt, that's how new discoveries are made.

[primexx]

There's always going to be doubt, that's how new discoveries are made.

don't bother with him, he craps in every science thread

[TheElite]

don't bother with him, he craps in every science thread

Hmm. Out of 30 threads on the main page, I've only "crapped" in one.

Don't mistake me for yourself, who ACTUALLY DOES crap in EVERY religion thread.