Search found 60 matches

by BobStein-VisiBone
Wed Jul 27, 2022 8:48 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Find the New Moon (2022 Jul 25)
Replies: 29
Views: 10116

Re: APOD: Find the New Moon (2022 Jul 25)

"Even though the Moon is above your horizon half of the time" is incorrect. depends on the phase, time of year and location How so? In December in the Northern Hemisphere, the full moon is above the horizon more than half of each day. Similar to the sun in summer. Though the moon can be a...
by BobStein-VisiBone
Sat Oct 24, 2020 12:22 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Tagging Bennu (2020 Oct 22)
Replies: 17
Views: 7080

Re: APOD: Tagging Bennu (2020 Oct 22)

A much better animation of the contact (101MB): https://svs.gsfc.nasa.gov/vis/a010000/a013700/a013744/A_samcam_approach_and_tag_37x_2.gif (be patient, after the first loop the animation will be quicker and smoother) Great discussion of the event by Scott Manley (12 min): https://youtu.be/cmQfWuFbLNg
by BobStein-VisiBone
Tue Sep 22, 2020 4:42 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Equinox in the Sky (2020 Sep 22)
Replies: 11
Views: 4428

Re: APOD: Equinox in the Sky (2020 Sep 22)

This photo would be helpful in any elementary school class, when helping students develop a fundamental understanding of astronomy. Imagine a class making an image like this from scratch, mapping the sun from solstice to solstice. Since the sun moves 0.4 degrees a day at the equinoxes, which is les...
by BobStein-VisiBone
Tue Sep 22, 2020 1:22 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Equinox in the Sky (2020 Sep 22)
Replies: 11
Views: 4428

Re: APOD: Equinox in the Sky (2020 Sep 22)

This photo would be helpful in any elementary school class, when helping students develop a fundamental understanding of astronomy. Imagine a class making an image like this from scratch, mapping the sun from solstice to solstice. Since the sun moves 0.4 degrees a day at the equinoxes, which is les...
by BobStein-VisiBone
Tue Sep 22, 2020 12:57 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Equinox in the Sky (2020 Sep 22)
Replies: 11
Views: 4428

Re: APOD: Equinox in the Sky (2020 Sep 22)

Trying to infer how far apart the images were taken. The sun images along the equinox path are spaced a little further than one diameter apart. By crude measurement of 49/21 pixels, or 2 and 1/3 diameters apart. The sun averages 32 minutes of arc in the sky so that's 74.7 minutes of arc between imag...
by BobStein-VisiBone
Fri Jan 31, 2020 2:54 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Goldilocks Zones and Stars (2020 Jan 31)
Replies: 24
Views: 8483

Re: APOD: Goldilocks Zones and Stars (2020 Jan 31)

Can someone explain x-ray irradiance and why smaller K and M stars give off more than the sun? I remember black body curves and don't understand why a smaller star would give off more. Thanks! I wondered this too. Those X-rays must not be part of the star's thermal radiation . Red dwarfs are known ...
by BobStein-VisiBone
Sat Feb 23, 2019 7:51 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Stars of the Triangulum Galaxy (2019 Feb 23)
Replies: 55
Views: 30881

Re: APOD: The Stars of the Triangulum Galaxy (2019 Feb 23)

Are all the "big" stars here part of the Milky Way? There's one bright one coincidentally appearing very near the center of M33 ... that's not in M33 right?

Image
Closeup of the center
by BobStein-VisiBone
Mon Jan 21, 2019 12:46 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Total Lunar Eclipse Video (2019 Jan 20)
Replies: 17
Views: 6959

Re: APOD: A Total Lunar Eclipse Video (2019 Jan 20)

So the Moon's apparent motion must also be subject to these shifts. Most welcome MarkBour. Yes you're right there must be a diurnal parallax of the moon too. Earth's umbra is a cone 870K miles long (1.4 gigameters) that every nighttime we slip inside of. I'm guessing the brownish circle in the vide...
by BobStein-VisiBone
Sun Jan 20, 2019 4:36 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Total Lunar Eclipse Video (2019 Jan 20)
Replies: 17
Views: 6959

Re: APOD: A Total Lunar Eclipse Video (2019 Jan 20)

I think the "intriguing pattern" is formed by virtue of the observer's location on the surface of a spinning Earth over the course of the two or three days straddling the eclipse. That is, it is topocentric, not geocentric. In other words, we're seeing the diurnal parallax of earth's shad...
by BobStein-VisiBone
Fri Jun 29, 2018 10:16 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Messier 24: Sagittarius Star Cloud (2018 Jun 29)
Replies: 10
Views: 6198

Re: APOD: Messier 24: Sagittarius Star Cloud (2018 Jun 29)

What makes the view yellowish on the right? Other views of M24 don't show this. What is scattering longer wavelengths?
by BobStein-VisiBone
Mon May 21, 2018 1:08 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Jupiter Cloud Animation from Juno (2018 May 21)
Replies: 12
Views: 10761

Re: APOD: Jupiter Cloud Animation from Juno (2018 May 21)

The original animation:
Image
(Click to enlarge)


From the 2-frame animation at europlanet plus a little translation, stretch, and rotate. But no further funny business.
by BobStein-VisiBone
Sun Jan 28, 2018 8:46 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Total Lunar Eclipse Over Tajikistan (2018 Jan 28)
Replies: 7
Views: 8143

Re: APOD: A Total Lunar Eclipse Over Tajikistan (2018 Jan 28)

At 0:38 in the video it is neat to watch the Moon move slightly leftward against the starry background, but the Earth's shadow remains fixed.
by BobStein-VisiBone
Thu Dec 07, 2017 1:00 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: All the Eclipses of 2017 (2017 Dec 07)
Replies: 9
Views: 9103

Re: APOD: All the Eclipses of 2017 (2017 Dec 07)

The "Saros Numbers" hyperlink seems incorrect and does not take one to another webpage ? I was just going to say this. It appears the date is missing a digit. https://apod.nasa.gov/apod/ap17811.html the "Saros numbers" link https://apod.nasa.gov/apod/ap170811.html should be
by BobStein-VisiBone
Wed Nov 29, 2017 4:36 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: M42: The Great Orion Nebula (2017 Nov 29)
Replies: 12
Views: 7712

Re: APOD: M42: The Great Orion Nebula (2017 Nov 29)

I've always thought of this nebula as Orion's Kneecap

Image
by BobStein-VisiBone
Wed Nov 15, 2017 9:27 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Comet Machholz Approaches the Sun (2017 Nov 13)
Replies: 22
Views: 9584

Re: APOD: Comet Machholz Approaches the Sun (2017 Nov 13)

I'd say "half as close" is a phrase to be avoided. I'm not saying it's great usage. Just that in this context it's obvious what it means. Here Comet Machholz is seen approaching the Sun much closer than Mercury ever does (; or to be specific: "half as close" ). Got it. The comet...
by BobStein-VisiBone
Thu Sep 28, 2017 5:49 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)
Replies: 29
Views: 9206

Re: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)

geckzilla wrote:
Chris Peterson wrote: I just meant that one day resolution is all APOD should ever need, but gravitational wave detections may need finer than that.
I still can't tell if we're joking or not.
Some days I wish there were an APOH.
by BobStein-VisiBone
Thu Sep 28, 2017 4:34 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)
Replies: 29
Views: 9206

Re: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)

since the ordered field significance allows for logical sorting. It does??? Ann That YYMMDD date code is "monotonic" in the sense that you can compare two codes alphabetically and know which one refers to an earlier time. So "171231" is less than "180101" in the same w...
by BobStein-VisiBone
Thu Sep 28, 2017 12:19 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)
Replies: 29
Views: 9206

Re: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)

What a fascinating read, that story Einstein's double reversal , about the changing minds over whether gravitational waves are real or abstract. ...in the end, Einstein had fully accepted the objections that had initially so upset him. And then Feynman's contribution: ...after the introduction of th...
by BobStein-VisiBone
Wed Sep 06, 2017 11:32 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Climber and the Eclipse (2017 Sep 06)
Replies: 36
Views: 20296

Re: APOD: The Climber and the Eclipse (2017 Sep 06)

I understand that Smith Rock is toward the south border of the totality zone, but still, how did that make the "diamond ring" appear where it does in the photo? Oh good angle on this question, haha pun intended. Simply by moving laterally one could "put" the diamond ring at any ...
by BobStein-VisiBone
Fri Apr 07, 2017 1:49 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Castle Eye View (2017 Apr 07)
Replies: 13
Views: 3954

Re: APOD: Castle Eye View (2017 Apr 07)

Explanation: The best known asterism in northern skies, The Big Dipper is easy to recognize , even when viewed upside down, though some might see a plough or wagon . What is this expression “upside down” of which you write? Wouldn't an upside down dipper be one positioned such that it can't hold wa...
by BobStein-VisiBone
Fri Apr 07, 2017 10:30 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Castle Eye View (2017 Apr 07)
Replies: 13
Views: 3954

Re: APOD: Castle Eye View (2017 Apr 07)

Correction to the first link, an article about The Big Dipper from the wayback machine.