APOD: The View Toward M101 (2016 Jan 21)

[inertnet]

Thanks everybody for the distance discussion. One thought I had when I originally asked my question was to ask M101 to please don't move while we took its picture

[Boomer12k]

Awesome image....

:---[===] *

[DavidLeodis]

I can get my mind around the comet being only "about 6 light-minutes from our fair planet" but M101 being "some 270 thousand light-centuries away" is mind boggling (though according to Nitpicker that is still only "about 1/2000th of the way to the edge of the observable universe"). There sure is a lot of space out there .

I wonder how much the image 'light' of M101 has spread out since it first came our way such perhaps that our view of M101 is blurred (like the light from a torch spreads out as it goes further from the torch).

[Nitpicker]

I wonder how much the image 'light' of M101 has spread out since it first came our way such perhaps that our view of M101 is blurred (like the light from a torch spreads out as it goes further from the torch).

Not blurred, but dimmed. Only a tiny portion of the light from M101 reaches Earth. Imagine the Earth intersecting the surface of a sphere of 27 million light years radius around M101. The surface area of the sphere represents all the light emitted by M101 in an instant, but the Earth occupies only the tiniest portion of that surface area, so we can only observe a tiny fraction of its light.

[DavidLeodis]

Thanks for your reply Nitpicker . Your "dimmed" is a more appropriate word than my "blurred".

[Chris Peterson]

I wonder how much the image 'light' of M101 has spread out since it first came our way such perhaps that our view of M101 is blurred (like the light from a torch spreads out as it goes further from the torch).

Not blurred, but dimmed. Only a tiny portion of the light from M101 reaches Earth. Imagine the Earth intersecting the surface of a sphere of 27 million light years radius around M101. The surface area of the sphere represents all the light emitted by M101 in an instant, but the Earth occupies only the tiniest portion of that surface area, so we can only observe a tiny fraction of its light.

It is interesting to consider true blurring and aberration, as well. The intervening space is not flat, but gravitationally "lumpy", and crisscrossed with gravitational waves. So there's actually some optical aberration, although over a mere 20 or 30 million light years, without any large intervening mass, that distortion is probably beyond our ability to measure, and certainly too small to be visible to our eyes in an image. But it's there.

[ta152h0]

would distances be more accurately calculated from distances, let's say Jupiter's orbit and 180 degrees apart ?

[Nitpicker]

would distances be more accurately calculated from distances, let's say Jupiter's orbit and 180 degrees apart ?

Not for galaxies, but the parallax method from Jupiter would allow us to measure accurate distances to more nearby stars (a bit further away), than the current Earth-bound parallax methods.

[neufer]

would distances be more accurately calculated from distances, let's say Jupiter's orbit and 180 degrees apart ?

Not for galaxies, but the parallax method from Jupiter would allow us to measure accurate distances to more nearby stars (a bit further away), than the current Earth-bound parallax methods.

While New Horizons is biding its time out around ~40 AU it would be nice for it to use LORRI's ~1 arcsec resolution to take some stereo images of nearby stars (i.e., stars <40 parsecs distant in directions more or less perpendicular to the direction of 2014 MU69).

<<New Horizons has maneuvered for a January 1, 2019 flyby of Kuiper belt object 2014 MU69 when it is 43.4 AU from the Sun. The Long-Range Reconnaissance Imager (LORRI) is a long-focal-length imager designed for high resolution and responsivity at visible wavelengths. The instrument is equipped with a 1024×1024 pixel by 12-bits-per-pixel monochromatic CCD imager with a 208.3 mm (8.20 in) aperture giving a resolution of 5 μrad (~1 arcsec).

In August 2013, it was proposed to use the radio-tracking data from New Horizons to discover indications on the position of a hypothesized trans-Neptunian planetary-sized body.>>