# Has there been any scientific study that agrees with Talmud Rosh Hashanna 20b's time difference?

I'm extracting from this M.Y. question:

In Talmud Bavli Rosh Hashanna 20b, R' Zeira quotes R' Nachman as saying:

כ"ד שעי מכסי סיהרא לדידן שית מעתיקא ותמני סרי מחדתא לדידהו שית מחדתא ותמני סרי מעתיקא

For 24 hours, the [moon] light is covered: For us [in Babylon] - 6 of the old [month] and 18 of the new [month]; for them [in Jerusalem] - 6 of the new and 18 of the old.

(Translation mine, with help from Rashi)

Has there been any scientific, Rabbinical or other study that agrees with this study or explains this differently?

I'm skeptical that there is actually a 6 hour difference. Here are some reasons why:

• At the equator, the earth rotates about 1,000 miles in 1 hour. The speed is slower as you move away from the equator. But, based on this, alone. Babylon is less than 6,000 miles from Jerusalem.

• A Google search revealed that the GPS coordinates of Babylon, Iraq. Latitude: 32.5352 Longitude: 44.4192.

The latitude of Jerusalem, Israel is 31.771959, and the longitude is 35.217018

We see that the latitude of the 2 places is about the same so the earth is rotating at about the same speed at both of these places.

I'm aware that current time zone divisions don't completely coordinate with the earth's rotational speed, but, I gather that it's pretty close. However, as the Talmudic statement was made long before a concept of "time zones" as we have it, I assume that they calculated this on observation and compared the observations in both of these places.

I'm asking how accurate they were based on current scientific calculations.

• If I recall correctly Maharal in Beer HaGoleh discusses this gemarra. Commented Jun 28, 2019 at 19:37
• @robev I occasionally review Art Scroll RH appendix that somewhat discusses this. It is tough understanding it, but it is a critical aspect of one of the 4 Rosh Hashanna postponement rules.
– DanF
Commented Jun 28, 2019 at 19:39
• Time zones aren't assigned according to latitude. The dividing lines go north/south, longitudinally. Lima, Peru and Chicago, Illinois have equivalent time zones despite being at significantly different latitudes (and consequently significantly different rotation speeds) Commented Jun 28, 2019 at 20:37