APOD: Venus and the Pleiades in April (2020 Apr 11)

[APOD Robot]

Venus and the Pleiades in April

Explanation: Shared around world in early April skies Venus, our brilliant evening star, wandered across the face of the lovely Pleiades star cluster. This timelapse image follows the path of the inner planet during the beautiful conjunction showing its daily approach to the stars of the Seven Sisters. From a composite of tracked exposures made with a telephoto lens, the field of view is also appropriate for binocular equipped skygazers. While the star cluster and planet were easily seen with the naked-eye, the spiky appearance of our sister planet in the picture is the result of a diffraction pattern produced by the camera's lens. All images were taken from a home garden in Chiuduno, Bergamo, Lombardy, Italy, fortunate in good weather and clear spring nights.

<< Previous APOD

This Day in APOD

Next APOD >>

[orin stepanek]

Venus looks like a star because of the diffraction spikes!

[heehaw]

So glad COVID-19 did not deprive us of this wonderful picture!

[Ann]

How can we be satisfied that significant changes have not taken place in the Pleiades being 400 years in the past compared with Venus's 2 minutes? Distance cannot be the only variable to describe difference.

DL Martin, you and I are getting a bit boring. I keep complaining about the color of APODs, and you keep reiterating that we can't trust pictures of objects that are far away, because the appearance of the objects may have changed since their light was emitted, so that the picture can't be trusted.

You think that picture is any good?

---

You know what, though? I'm sure the others are getting rather tired of us. Therefore, in order to make the others put up with me, I'm trying to show my lack of enthusiasm at the color of an APOD by saying that I prefer another picture of the same object. That is annoying too, I'm sure, but it's better than me telling everyone that the color of the APOD does not please me.

Perhaps you, too, could try to tell us what kind of pictures you would like to see, instead of constantly grumbling that you can't accept the - I don't know, veracity? - of the APOD?

Ann

[sillyworm 2]

DL....it is a little frustrating....but it's all we have and all we will ever have.Is not the fact that we see them at all reward enough?!

[DonB312]

Hi DL,

Take a look at this Proper Motion Simulator. Click on the "Pleiades proper motion" link. Once you see the stars, immediately press the P key to pause the simulation. Now click the + button at the upper left to advance the simulation 1000 years per click.

As you will see, the Pleiades does not change much even over a span of several thousand years. So when we see it as it was when its light was emitted 450 years ago, we can rest assured that it has not changed much since then (at least not enough to notice unless you track it with great precision over a period of many years).

Even Barnard's Star, (the star with the fastest known proper motion) only moves a short distance on the sky each century. On the page with the "Pleiades proper motion link", if you click the "Barnard's Star" link you can play with a simulation of this.

Also, astronomers have a very precise understanding of the lifetimes of stars and galaxies, galactic rotation speeds, etc. and based on that understanding it is quite certain that most of what we see in the nearby universe still exists and has not changed perceptibly to the naked eye over time spans of several hundreds or even thousands of years (with the exception of things like supernovas, planetary nebulae, etc.)

Finally, back to the proper motion simulator, if you press the M key it will bring up many options that you can adjust to vary the parameters (speed per iteration, etc.) of the simulation.

ETA: If you were to look at the Milky Way from Andromeda, you would indeed see it as it was about 25 million years before you observed it. But that is a very short time relative to the immense time and distance scales of the universe. In the time it takes a photon to travel from the Milky Way and arrive at Andromeda (about 25 million years) the sun will have only advanced about a 10th of the way along its orbit around the Milky Way. And when you looked at the Milky Way from Andromeda, the large scale structure of the galaxy would look quite similar to the way it would look if you could see it "now" even though it is 25 million years older than it was when the photon began it's journey to you.

Don

[Chris Peterson]

How can we be satisfied that significant changes have not taken place in the Pleiades being 400 years in the past compared with Venus's 2 minutes? Distance cannot be the only variable to describe difference.

DL Martin, you and I are getting a bit boring. I keep complaining about the color of APODs, and you keep reiterating that we can't trust pictures of objects that are far away, because the appearance of the objects may have changed since their light was emitted, so that the picture can't be trusted.

If you're boring, at least it's simply a matter of aesthetic values. DL Martin is just plain scientific ignorance. His posts need to be moderated out on the basis of coming from a crank.

[geckzilla]

welcome to science hell

In case there's any question, DL Martin is Tony in this example. Also, DL Martin, I am pretty tired of dealing with your reported posts. If you don't stop trying to badly explain spacetime to us on your own from here on out, you might find that you will be stopped by other means. Once was fine, a dozen times or every time an APOD fails to satisfy your specific criteria is just plain annoying. Like, I just don't need to deal with someone's personal campaign against APOD. If you don't like APOD, don't view it. Or at least don't read the descriptions. You're not going to force it to change by doing this.

[Ann]

I'd like to comment on the APOD. I like it a lot. It's nice to see the path of Venus across the patch of sky where we see the Pleiades. And of course, me being me, I'm very happy to see the blue color of the brightest members of the deceptively faint stars of the Pleiades (deceptively faint, compared with the warm-white Sun-reflecting glare of very nearby Venus).

Very nice!

Ann

[geckzilla]

DL went the route of troll. If you see 'em just report it. He doesn't use an account and I expect at least a few IP shuffles.

[neufer]

In case there's any question, DL Martin is Tony in this example.

• Science is all about explaining as much as possible as simply as possible.

<<Laplace went in state to Napoleon to present a copy of his work [Traité de mécanique céleste]. Someone had told Napoleon that the book contained no mention of the name of God; Napoleon, who was fond of putting embarrassing questions, received it with the remark, 'M. Laplace, they tell me you have written this large book on the system of the universe, and have never even mentioned its Creator.' Laplace drew himself up and answered bluntly, Je n'avais pas besoin de cette hypothèse-là. ("I had no need of that hypothesis.") >>

[Ann]

Science is all about explaining as much as possible as simply as possible.

Click to play embedded YouTube video.

The Big Dipper through time.

Snapshot of the 'current appearance' of the Big Dipper. Photo: Akira Fuji.

---

Occam's razor.

---

Which is why we love Occam's razor. Or, in in the case of the Big Dipper or even the Pleiades, it's why we love "the current appearance" of cosmic objects.

Ann

[geckzilla]

It seemed obvious to me, too, but I learned a long time ago that jokes are fairly often misunderstood online, even here. Especially here.

[neufer]

It seemed obvious to me, too, but I learned a long time ago that
jokes are fairly often misunderstood online, even here. Especially here.

• Gee, Officer Gecke, we're very upset;
  We never had the love that ev'ry child oughta get.
  We ain't no delinquents,
  We're misunderstood.
  Deep down inside us there is good!