Talk:Lunar distance

removed

I removed a See also link: Nevil Maskelyne. He worked on Lunar distance (navigation) which is an angle, not the distance to the Moon. Bubba73 (talk), 04:32, 1 December 2007 (UTC)

History

I saw a tv show where it said that the Moon was during the dinosaur era much closer to Earth, making the days shorter. I can´t find nothing of this. I don's peak english very well.--Comu_nacho (spanish speaker) (talk) 18:48, 17 June 2010 (UTC)

What is the point of this article?

Everything in this article is covered by other articles on the Moon, two of which (Orbit of the Moon, Lunar Laser Ranging Experiment) are even linked from this article. treesmill (talk) 20:06, 10 March 2012 (UTC)

Near-Earth asteroids use this term all the time to clarify close approaches to the Earth. -- Kheider (talk) 20:10, 10 March 2012 (UTC)

Which part of that is not covered by the other articles? treesmill (talk) 13:47, 11 March 2012 (UTC)

Distance between centres?

Does "the distance from the Earth to the moon" mean the distance between their centres?

The article states that the Moon is spiraling away from the Earth at an average rate of 3.8 cm per year. With this level of achievable accuracy, why is the Lunar Distance specified to the nearest kilometer and not, say, to the nearest meter?

(1) Yes, between the centers. (2) I'm not sure. It may be that it is easier to measure the rate at which it is receeding than measuring the absolute distance that accurately. Bubba73 (talk), 01:28, 30 May 2007 (UTC)

Because of the eccentricity of the Moon's orbit around the Earth, the distance is varying all the time. A quick calculation suggests that the distance varies at an average of about 35 m/s (slower near perigee and apogee, faster in between). On top of that, the distance to the Moon at perigee and apogee varies considerably, so quoting the distance more accurately would be spurious. treesmill (talk) 20:17, 10 March 2012 (UTC)

File:Earth-Moon.png to appear as POTD

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Picture of the day

Lunar distance is a measurement of the distance from the Earth to the Moon. This diagram shows the distance, averaging 384,400 km (238,900 mi), to scale, as well as the Earth and the Moon (scroll to see the entire image).Model: Nickshanks

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Best known value

It is stated by the lunar laser ranging experiment that the mean lunar distance can be measured to sub-millimeter precision. Can anybody find a reference to a sub-mm 384402XXX.XXXX +/- 0.000Y (+3.8cm/yr) value? Hadron137 (talk) 19:21, 26 April 2016 (UTC)

Sub-mm is wrong. I changed it. LunaJim (talk) 17:24, 30 May 2021 (UTC)

Images of moon at least and greatest distance from the earth seem wrong

The least and greatest distances of the moon from the earth are roughly in the ratio of 7:8. The images of the moon at least and greatest distance, in the article, seem to be more like 4:5. The ratio of the apparent diameters should equal the ratio of lest to greatest distances. So the images shown seem to be in error. ClarkoEye (talk) 00:55, 30 March 2017 (UTC)

I think the image is correct. Simply comparing the ratio of perigee to apogee gives a value of ${\frac {356500km}{406700km}}=0.876$. The image of the larger moon is about 394 pixels diameter, and the smaller image is 346 pixels. ${\frac {346px}{394px}}=0.878$, which is in good agreement with the expected value.

Using the ratio parigee/apogee is valid since the moon is far away compared to its size, but for a more accurate analysis, the apparent size should be used instead of the distance. The apparent size is calculated as $2*\arcsin \left({\frac {radius}{distance}}\right)$. Using the radius of the moon as 1737 km, this gives a value of 0.5586° at perigee and 0.4896° at apogee. This ratio is consistent with expectations, ${\frac {0.4896}{0.5586}}=0.876$, and agrees nicely with the image. Hadron137 (talk) 22:15, 8 September 2017 (UTC)

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Lunar communications delay -- suggested sub-section

A number of vehicles have been sent to the moon, with some orbiting as satellites today. The most dramatic lunar orbits have been the manned missions between 1968 and 1972. All communications experience(d) predictable radio delays which align(ed) with established distances. The delay is not extraordinary but the communication distance is still notable, and the manned missions are so far the only times that people have measured the moon distance when holding both ends of the metaphorical tape measure. I was expecting that there would be a mention here about radio / light distance and timing; when I find this elsewhere I might add this sub-section. --GeeBee60 (talk) 12:48, 16 October 2018 (UTC)

Yes, feel free to add property cited content. You will find information about radio & light timing at lunar laser ranging experiment. Hadron137 (talk) 05:40, 23 November 2019 (UTC)

Receding

Can you explain this? Or too technical?

Article says;

The current rate of recession is 3.830±0.008 cm per year. … a rate of 3.8 cm/year would imply that the Moon is only 1.5 billion years old. … the rate of recession may continue to accelerate.

I get 10 billion from;

Distance now (3.84E+08 metre),

recedes per year (3.83E-02 metre) =>

Years (1.00E+10).

I presume the rate started (much) higher, and has diminished to 3.8 cm/yr.

Why would it accelerate?

What “should” the rate be if it started 4.5 billion years ago?

A table with days in a year, and distance to moon (since year 0), would be nice. Like this Day#Longitudinal_change.

MBG02 (talk) 06:42, 11 February 2022 (UTC)

possible answer at ΔT_(timekeeping)#Geological_evidence;

… the day was 21.9 hours long and there were 13.1 synodic months/year and 400±7 solar days/year. The average recession rate of the Moon between 620 million years ago and now has been 2.17 cm/year… the present high rate may be due to near resonance between natural ocean frequencies and tidal frequencies.

MBG02 (talk) 09:18, 11 February 2022 (UTC)

Requested move 24 September 2023

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: moved. (closed by non-admin page mover) Frostly (talk) 02:30, 1 October 2023 (UTC)

---

• Lunar distance (astronomy) → Lunar distance
• Lunar distance → Lunar distance (disambiguation)

– Appears to be the primary topic of "Lunar distance". As seen from and compared on two Wikinav pages, the one for astronomy has far more traffic than the one for navigation. A hatnote should be put on the page after the move. What do we think here? Wikiexplorationandhelping (talk) 22:25, 23 September 2023 (UTC)

Note: WikiProject Vital articles has been notified of this discussion. Wikiexplorationandhelping (talk) 22:26, 23 September 2023 (UTC)

Note: WikiProject Astronomy has been notified of this discussion. Wikiexplorationandhelping (talk) 22:26, 23 September 2023 (UTC)

Note: WikiProject Measurement has been notified of this discussion. Wikiexplorationandhelping (talk) 22:27, 23 September 2023 (UTC)

Note: Disambiguations are not eligible to be moved to through a move request, so Lunar distance → Lunar distance (disambiguation) has been added to the request. EggRoll97 ^(talk) 01:31, 24 September 2023 (UTC)

That's not the case. If moved according to the original proposal, the dab page would simply be deleted. If there's a primary topic and only one other article, a dab page is not needed. Station1 (talk) 17:58, 24 September 2023 (UTC)

• Support per nom and per WP:TWODABS, which can handle this with a hatnote. BD2412 T 04:59, 24 September 2023 (UTC)
• Support. Pageviews show this article to be the consistent WP:primary topic in a WP:ONEOTHER situation. A hatnote is all that is required. (The current dab page should simply be deleted as originally proposed.) Station1 (talk) 17:58, 24 September 2023 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.