Orion Nebula Gets New Milepost Marker, Now Closer

twilight30 writes "Discovery News is reporting that 'One of the most famous and scrutinized heavenly objects is 10 to 20 percent closer than we thought, say two teams of radio astronomers who have made some of the most precise cosmic distance measurements ever, with a telescope nearly as big as Earth. The Orion Nebula is the closest major stellar nursery to Earth, so it has been heavily studied to learn about the lives of stars. Its distance from Earth, however, has long been a matter of uncertainty, with an estimate made about 25 years ago in need of revision.'"

Comments

Re:"a telescope nearly as big as Earth"

[opus]

The VLBA was aimed at one of the few radio-wave emitting stars in Orion, which was viewed twice in a single a year. The almost 200-million-mile width of Earth's orbit around the sun allowed the VLBA to serve as one eye, then again as the other eye six months later.

Wouldn't that be a telescope 200-million-miles wide, using the same poetic license that led them to say they used a telescope as big as the earth.

Re:question:

[siddesu]

the sun travels around the galactic center at about 20km/s. even assuming than sun and orion nebula travel away from each other at this speed, for 6 months they'd have moved away at about 6 billion km. this is about 0.00068 light years. since the distance is estimated at 1250+ l.y. give or take 50-60, the error due to the relative movement of the two objects seems accounted for.

Closer than we thought...

[LordP]

Measured incorrectly, or has the Orion Nebula just been sneaking closing over the last 25 years?

Re:Closer than we thought...

[davburns]

Bower and his colleagues came up with a distance of 1,270 light-years, give or take 76 light-years. That compares with the previous estimate of 1,565 light-years, give or take 266.

There's still overlap in the uncertainties of the measurements. So it wasn't incorrectly measured, just measured with a 17% error margin. The only ones who are incorrect are the people who quote the estimate without including the uncertainty.

Re:"a telescope nearly as big as Earth"

[Anonymous Coward]

Saying that the telescope was "nearly as big as Earth" is dead wrong. The effective aperture of the telescope, for this purpose, is twice the radius of the orbit of Earth around the sun, or almost 200 million miles. Gotta love those science reporters...

nah, not true

[someone1234]

This won't save your ass when the distance is only 1mm :)