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I've been using an IOS app to predict visibility of the Milky Way.

I'm planning a trip to capture the Milky Way on 9th March 2015, but the app shows the visibility will be very weak on that date.

The Moon doesn't even rise until 9:12am.

Does the Moon phase still affect the visibility of the Milky Way even if it is not above the horizon?

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  • $\begingroup$ Re The Moon doesn't even rise until 9:12am. -- That's backwards! That's when the Moon will set. $\endgroup$
    – David Hammen
    Feb 24, 2015 at 15:16

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Moon Phase

With the moon phase, it's going to be in Waning Gibbous on March 9th, so it will be reflecting a lot of light back to earth. Any light that interferes with the sky will make dimmer objects harder to see.

enter image description here

The Moon's reflectivity figures taken from here:

Fraction of the moon: 0.61371425766053

Illumination of the moon disk: 88 %

Location

It will also depend a lot on your home location (hemisphere) as to the position of the Milky Way at different times. Your proximity to any light pollution will of course have an impact, as living on the outskirts of a city myself, it is impossible to view the Milky Way. Only when in very rural areas on clear nights have I had a good view of it.

New Moon

On the 20th March there is a New Moon, so this may be a more opportune time to try to capture it.

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  • $\begingroup$ Thank you Tanner. By the way, the link you have on your answer is for 03/09/13, not 03/09/15. $\endgroup$
    – Moon
    Feb 23, 2015 at 18:19
  • $\begingroup$ This is the wrong answer. $\endgroup$
    – David Hammen
    Feb 24, 2015 at 14:27
  • $\begingroup$ @DavidHammen can you elaborate? I'm not an expert in any way, this was just my view point on the issue. $\endgroup$
    – Tanner
    Feb 24, 2015 at 14:30
  • $\begingroup$ @Tanner - The questioner has moonrise and moonset mixed up. There'll be a big fat gibbous Moon in the sky at night on March 9, especially late, late at night, which is when the brightest part of the Milky Way would otherwise be visible. $\endgroup$
    – David Hammen
    Feb 24, 2015 at 14:53
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Does the Moon phase still affect the visibility of the Milky Way even if it is not above the horizon?

No. The main culprit is the Sun. Lunar twilight is extremely weak. It essentially ends when the Moon goes below the horizon. See this answer at the physics stackexchange.

One problem is that this is the wrong time of the year to be looking at the Milky Way. The brightest part of the bands we call the Milky Way is the core, and that's best seen from May to October. Right now the core of the Milky Way is visible from the Northern Hemisphere for only the last few hours before sunrise, and it's not very high on the horizon.

There is another problem, however ...

The Moon doesn't even rise until 9:12am.

That's backwards. On March 8-10 2015, the Moon rises between 10:00 PM to midnight and sets between 9:00 AM to 10:30 AM. The Moon will be big and fat in the wee hours of the morning sky, which is when the core of the Milky Way would otherwise be visible.

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