Starship Asterisk*

Tetenterre wrote:Beautiful image, but surely the red light that reaches the Moon is transmitted and refracted, not scattered, by Earth's atmosphere - it is the light at the blue end of the spectrum that is scattered.

Chris Peterson wrote:

Tetenterre wrote:
Beautiful image, but surely the red light that reaches the Moon is transmitted and refracted, not scattered, by Earth's atmosphere - it is the light at the blue end of the spectrum that is scattered.

There is minimal refraction. The light from the Sun is both scattered and absorbed in the atmosphere. The amount of scatter is wavelength dependent, with shorter wavelengths scattering differently than longer wavelengths. If the red light were not scattering, it would not be visible from the Moon. I expect you also get a redder eclipse when the Earth has lots of clouds along its terminator to scatter more light. (Just like sunsets are more obviously red when you have clouds.)

• Up to 1º refraction of UNscattered 0.5º wide red sunlight around a 2º wide Earth
  + some secondary scattering & further refraction of that:

https://en.wikipedia.org/wiki/Atmospheric_refraction wrote:

---

<<Atmospheric refraction of the light from a star is zero in the zenith, less than 1′ (one arc-minute) at 45° apparent altitude, and still only 5.3′ at 10° altitude; it quickly increases as altitude decreases, reaching 9.9′ at 5° altitude, 18.4′ at 2° altitude, and 35.4′ at the horizon. On the horizon refraction is slightly greater than the apparent diameter of the Sun, so when the bottom of the sun's disc appears to touch the horizon, the sun's true altitude is negative.>>

https://en.wikipedia.org/wiki/Lunar_eclipse#Lunar_eclipse_appearance wrote:

[b][color=#FF0000]From the Moon, a lunar eclipse would show a ring of reddish-orange light surrounding a dark Earth in the sky.[/color][/b]

---

<<The moon does not completely disappear as it passes through the umbra because of the refraction of sunlight by the Earth's atmosphere into the shadow cone; if the Earth had no atmosphere, the Moon would be completely dark during an eclipse. The reddish coloration arises because sunlight reaching the Moon must pass through a long and dense layer of the Earth's atmosphere, where it is scattered. Shorter wavelengths are more likely to be scattered by the air molecules and the small particles, and so by the time the light has passed through the atmosphere, the longer wavelengths dominate. This resulting light we perceive as red. This is the same effect that causes sunsets and sunrises to turn the sky a reddish color; an alternative way of considering the problem is to realize that, as viewed from the moon, the sun would appear to be setting (or rising) behind the Earth.

The amount of refracted light depends on the amount of dust or clouds in the atmosphere; this also controls how much light is scattered. In general, the dustier the atmosphere, the more that other wavelengths of light will be removed (compared to red light), leaving the resulting light a deeper red color. This causes the resulting coppery-red hue of the moon to vary from one eclipse to the next. Volcanoes are notable for expelling large quantities of dust into the atmosphere, and a large eruption shortly before an eclipse can have a large effect on the resulting color.>>

neufer wrote:

Chris Peterson wrote:There is minimal refraction. The light from the Sun is both scattered and absorbed in the atmosphere. The amount of scatter is wavelength dependent, with shorter wavelengths scattering differently than longer wavelengths. If the red light were not scattering, it would not be visible from the Moon. I expect you also get a redder eclipse when the Earth has lots of clouds along its terminator to scatter more light. (Just like sunsets are more obviously red when you have clouds.)

Up to 1º refraction of UNscattered 0.5º wide red sunlight around a 2º wide Earth

stevie wrote:Does anyone know when will be the next Super Blue Black Moon Total Solar Eclipse?

heehaw wrote: Am I just being a jerk, when I say there is a full moon once every month, and ALL these stupid adjectives should be flushed?

Chris Peterson wrote:

neufer wrote:

Chris Peterson wrote:
There is minimal refraction. The light from the Sun is both scattered and absorbed in the atmosphere. The amount of scatter is wavelength dependent, with shorter wavelengths scattering differently than longer wavelengths. If the red light were not scattering, it would not be visible from the Moon. I expect you also get a redder eclipse when the Earth has lots of clouds along its terminator to scatter more light. (Just like sunsets are more obviously red when you have clouds.)

Up to 1º refraction of UNscattered 0.5º wide red sunlight around a 2º wide Earth

Yup. Minimal refraction. Virtually all of the red light we see on the Moon is the product of scattering, most of it from clouds and smoke particles.

• With a 2º wide Earth (and a 0.5º wide sun)
  1º of refraction is all that is needed to
  irradiate even a close umbrally eclipsed supermoon.
  
  Scattering augments refraction not vice versa.

https://www.etymonline.com/word/umbrage wrote:
umbrage (n.) early 15c., "shadow, shade," from Middle French ombrage "shade, shadow," from noun use of Latin umbraticum "of or pertaining to shade; being in retirement," neuter of umbraticus "of or pertaining to shade," from umbra "shade, shadow." Many figurative uses in 17c.; main remaining one is the meaning "suspicion that one has been slighted," first recorded 1610s; hence phrase to take umbrage at, attested from 1670s.

neufer wrote:

Chris Peterson wrote:

Tetenterre wrote:
Beautiful image, but surely the red light that reaches the Moon is transmitted and refracted, not scattered, by Earth's atmosphere - it is the light at the blue end of the spectrum that is scattered.

There is minimal refraction. The light from the Sun is both scattered and absorbed in the atmosphere. The amount of scatter is wavelength dependent, with shorter wavelengths scattering differently than longer wavelengths. If the red light were not scattering, it would not be visible from the Moon. I expect you also get a redder eclipse when the Earth has lots of clouds along its terminator to scatter more light. (Just like sunsets are more obviously red when you have clouds.)

• Up to 1º refraction of UNscattered 0.5º wide red sunlight around a 2º wide Earth
  + some secondary scattering & further refraction of that:

https://en.wikipedia.org/wiki/Atmospheric_refraction wrote:

---

<<Atmospheric refraction of the light from a star is zero in the zenith, less than 1′ (one arc-minute) at 45° apparent altitude, and still only 5.3′ at 10° altitude; it quickly increases as altitude decreases, reaching 9.9′ at 5° altitude, 18.4′ at 2° altitude, and 35.4′ at the horizon. On the horizon refraction is slightly greater than the apparent diameter of the Sun, so when the bottom of the sun's disc appears to touch the horizon, the sun's true altitude is negative.>>

https://en.wikipedia.org/wiki/Lunar_eclipse#Lunar_eclipse_appearance wrote:

[b][color=#FF0000]From the Moon, a lunar eclipse would show a ring of reddish-orange light surrounding a dark Earth in the sky.[/color][/b]

---

<<The moon does not completely disappear as it passes through the umbra because of the refraction of sunlight by the Earth's atmosphere into the shadow cone; if the Earth had no atmosphere, the Moon would be completely dark during an eclipse. The reddish coloration arises because sunlight reaching the Moon must pass through a long and dense layer of the Earth's atmosphere, where it is scattered. Shorter wavelengths are more likely to be scattered by the air molecules and the small particles, and so by the time the light has passed through the atmosphere, the longer wavelengths dominate. This resulting light we perceive as red. This is the same effect that causes sunsets and sunrises to turn the sky a reddish color; an alternative way of considering the problem is to realize that, as viewed from the moon, the sun would appear to be setting (or rising) behind the Earth.

The amount of refracted light depends on the amount of dust or clouds in the atmosphere; this also controls how much light is scattered. In general, the dustier the atmosphere, the more that other wavelengths of light will be removed (compared to red light), leaving the resulting light a deeper red color. This causes the resulting coppery-red hue of the moon to vary from one eclipse to the next. Volcanoes are notable for expelling large quantities of dust into the atmosphere, and a large eruption shortly before an eclipse can have a large effect on the resulting color.>>

neufer wrote:

Chris Peterson wrote:

neufer wrote:
Up to 1º refraction of UNscattered 0.5º
wide red sunlight around a 2º wide Earth

Yup. Minimal refraction. Virtually all of the red light we see on the Moon is the product of scattering, most of it from clouds and smoke particles.

• With a 2º wide Earth (and a 0.5º wide sun)
  1º of refraction is all that is needed to
  irradiate even a close umbrally eclipsed supermoon.
  Scattering augments refraction not vice versa.

Gosh wrote:
Does that mean the moon Trumps the earth?

bystander wrote:

heehaw wrote: Am I just being a jerk, when I say there is a full moon once every month, and ALL these stupid adjectives should be flushed?

There is not a full moon this month!

neufer wrote:

https://en.wikipedia.org/wiki/Lunar_eclipse#Lunar_eclipse_appearance wrote: (Nice simulated image, just above.)

• Surveyor 3 was the first lunar spacecraft to image such an eclipse http://www.alpo-astronomy.org/eclipse/o ... pter15.htm
• There is an image from the Japanese probe Kaguya that Phil Plait posted on his Bad Astronomy site:
  http://www.kaguya.jaxa.jp/image/communi ... 218_01.jpg
• Cassini sent a beautiful view of this -- for Saturn, not Earth: https://saturn.jpl.nasa.gov/resources/5918/
• The astronauts returning from the Moon in 1969 (particularly Apollo 12 astronaut Alan Bean reported on it). https://science.nasa.gov/science-news/s ... nareclipse

BillBixby wrote:

Touché! And here I am, Mr. Calendar! http://hankehenryontime.com/html/today.html

I guess I fail to understand the linked calendar. It says today is Thursday, Feb second.
My calendar says today is Thursday, Feb first. Is there humor involved?

BillBixby wrote:Touché! And here I am, Mr. Calendar! http://hankehenryontime.com/html/today.html

BillBixby wrote:

BillBixby wrote:Touché! And here I am, Mr. Calendar! http://hankehenryontime.com/html/today.html

I guess I fail to understand the linked calendar. It says today is Thursday, Feb second.
My calendar says today is Thursday, Feb first. Is there humor involved?

Guest wrote:
So I was trying to explain to the kids why the moon (and planets, etc) are round. I ran into a problem trying to explain why gravity works without expending energy.