APOD: Gaia: Here Comes the Sun (2016 Sep 26)

[Wolf]

Tdere is another Wolf ere ?

Ja, virtually... but traveling at about 6 kpc/s

If my math is not mistaken, this means this APOD featured traveler is moving at about 617 billion times the speed of light.

It certainly puts into question interstellar travel let alone intergalactic travel... on the other-hand, "where are they?"

[neufer]

Tdere is another Wolf ere ?

Ja, virtually... but traveling at about 6 kpc/s

If my math is not mistaken,
this means this APOD featured traveler is moving at about 617 billion times the speed of light.

Or the APOD featured traveler is moving at about (1.0 - 1.3x10^-24) times the speed of light
while measuring seconds using his own veerrryyyy slow clock.

[Wolf]

Or the APOD featured traveler is moving at about (1.0 - 1.3x10^-24) times the speed of light
while measuring seconds using his own veerrryyyy slow clock.

... or her slow clock... or... not sure...

[johnnydeep]

Oh, if only we could really travel as fast as is shown in this video, relativity be damned!

[Ann]

What would it look like to return home from outside our galaxy? Okay, so... If you were outside our galaxy, how could you find your way home (even if it was possible for you to travel impossibly fast)?

It's not as if our Sun looks that remarkable from outside or galaxy, and it's not as if it's holding up a sign to stand out in a crowd, and it is not as if our galaxy is providing a GPS with that teardrop-shaped thing pointing at the Sun to guide wayward travellers on their way home.

Don't hold your breath looking for that sort of sign on your way back home from intergalactic space!

Or you mean Gaia would provide that sort of detailed Milky Way map to actually make it possible for intergalactic travellers to find their way home? Really?

Ann

[johnnydeep]

What would it look like to return home from outside our galaxy? Okay, so... If you were outside our galaxy, how could you find your way home (even if it was possible for you to travel impossibly fast)?

It's not as if our Sun looks that remarkable from outside or galaxy, and it's not as if it's holding up a sign to stand out in a crowd, and it is not as if our galaxy is providing a GPS with that teardrop-shaped thing pointing at the Sun to guide wayward travellers on their way home.


The Sun is here ESA Gaia DPAC.png


Don't hold your breath looking for that sort of sign on your way back home from intergalactic space!

Or you mean Gaia would provide that sort of detailed Milky Way map to actually make it possible for intergalactic travellers to find their way home? Really?

Ann

How about using GPPS to navigate home? That would be the Galactic Pulsar Positioning System™. See https://skyandtelescope.org/astronomy-n ... -missions/.

This was also how the Sun's position in the galaxy was etched on the Pioneer and Voyager records/plaques:

The radial pattern on the left of the plaque shows 15 lines emanating from the same origin. Fourteen of the lines have corresponding long binary numbers, which stand for the periods of pulsars, using the hydrogen spin-flip transition frequency as the unit. Since these periods will change over time, the epoch of the launch can be calculated from these values.

The lengths of the lines show the relative distances of the pulsars to the Sun. A tick mark at the end of each line gives the Z coordinate perpendicular to the galactic plane.

If the plaque is found, only some of the pulsars may be visible from the location of its discovery. Showing the location with as many as 14 pulsars provides redundancy so that the location of the origin can be triangulated even if only some of the pulsars are recognized.

Click to view full size image