Starship Asterisk*

Nitpicker wrote:
Indeed, and the time interval between when it first became visible on Earth and the present time,
is typically the most useful description of its age, regardless of its distance.

• Through the Looking Glass : Chapter 8: “It’s my own Invention”

‘You are sad,’ the Knight said in an anxious tone: ‘let me sing you a song to comfort you.’

‘Is it very long?’ Alice asked, for she had heard a good deal of poetry that day.

‘It’s long,’ said the Knight, ‘but very, very beautiful. Everybody that hears me sing it — either it brings the tears into their eyes, or else — ’

‘Or else what?’ said Alice, for the Knight had made a sudden pause.

‘Or else it doesn’t, you know. The name of the song is called “Haddocks’ Eyes.”’

‘Oh, that’s the name of the song, is it?’ Alice said, trying to feel interested.

‘No, you don’t understand,’ the Knight said, looking a little vexed. ‘That’s what the name is called. The name really is “The Aged Aged Man.”’

‘Then I ought to have said “That’s what the song is called”?’ Alice corrected herself.

‘No, you oughtn’t: that’s quite another thing! The song is called “Ways and Means”: but that’s only what it’s called, you know!’

‘Well, what is the song, then?’ said Alice, who was by this time completely bewildered.

‘I was coming to that,’ the Knight said. ‘The song really is “A-sitting On A Gate”: and the tune’s my own invention.’

Nitpicker wrote:Both the distance to the object and the year it was first visible from Earth, are mere estimations. They are not precise numbers. So, it makes sense to refer to the age of such objects with respect to our own time frame.

Misha wrote:

Chris Peterson wrote:

Guest wrote:A small correction, if I may. If the supernova remanant is 40,000 years old, and it is 3000 light years distant, then it light first reached Earth 37,000 years ago, not 40,000.

It doesn't matter how far away it is. Astronomical events are dated based on observation. If the remnant is determined to be 40,000 years old, that means the supernova would have been observed here that long ago.

Impossible. If it's 3,000 LY away and the supernova blew 40,000 years ago, we wouldn't see it until 3,000 years after it happened.

DL MARTIN wrote:if one doesn't allow for the time light travels, then one is denying context. Astronomy then becomes a very expensive hobby that should be self-pay.

Misha wrote:

Chris Peterson wrote:

Guest wrote:
A small correction, if I may. If the supernova remnant is 40,000 years old, and it is 3000 light years distant, then it light first reached Earth 37,000 years ago, not 40,000.

It doesn't matter how far away it is. Astronomical events are dated based on observation. If the remnant is determined to be 40,000 years old, that means the supernova would have been observed here that long ago.

Impossible. If it's 3,000 LY away and the supernova blew 40,000 years ago, we wouldn't see it until 3,000 years after it happened.

Misha wrote:
“This isn't right. This isn't even wrong.” — Wolfgang Pauli, on a paper submitted by a physicist colleague

Chris Peterson wrote:

Guest wrote:A small correction, if I may. If the supernova remanant is 40,000 years old, and it is 3000 light years distant, then it light first reached Earth 37,000 years ago, not 40,000.

It doesn't matter how far away it is. Astronomical events are dated based on observation. If the remnant is determined to be 40,000 years old, that means the supernova would have been observed here that long ago.

Loren Acton wrote:Surely not ionized hydrogen as protons have no optical emission. I suppose you mean the H-alpha line of neutral hydrogen.

Guest wrote:A small correction, if I may. If the supernova remanant is 40,000 years old, and it is 3000 light years distant, then it light first reached Earth 37,000 years ago, not 40,000.