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Reading that the Leonids meteor shower is almost upon us, I clicked some links (e.g. EarthSky.org and NatGeo) to read more of the prediction; especially the part about when to best view them.

I had a Déjà vu when I saw "early morning hours" because it seemed to me that "that's what they always say".

I'm guessing that it's not a coincidence that the constellation for which the shower is named always seems to rise around or after midnight at the time of year when the shower occurs.

So I'd like to ask if this is true, that they pretty much always are best viewed after midnight (except when issues of weather or the Moon interfere), and if there has ever been a shower where this wasn't the case — one that was best viewed before midnight.

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The Draconids have a radiant that, from the the Northerly Latitudes (N America or Europe) is highest in the sky in the early evening of October 7th or 8th. This means that unlike most showers (which are best before dawn) the Draconids are most active after dusk. They are not visible to many Southern Hemisphere observers.

They are capable of producing short-spikes of activity, and there is a prediction that 2018 may generate a meteor storm, with over 1000 meteors per hour. It will coincide with a new moon, so could be rather special.

Astronomy.com

Earthsky.org

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  • $\begingroup$ Bingo! You've found one, thanks! I also noticed that in your Astronomy.com link it says "Most researchers agree that a full-fledged meteor storm — defined as 1,000 meteors an hour or more — will occur in 2018. Draconids are slow-moving meteors, encountering Earth at less than 12 miles (20 km) per second, and they typically are faint." $\endgroup$ – uhoh Nov 18 '17 at 2:30
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Not that I know of, and it would somewhat surprise me.

The number of meteors from a shower you will see depends on the time of night through a number of reasons (not considering the weather and the moon):

  1. The distribution of meteoroids on Earth's orbit is not homogeneous. The highest potential occurs when Earth moves through the peak of the distribution. This is associated with a certain time on Earth.
  2. Meteors from a shower appear tot come from the same spot in the sky. This spot is called the radiant and moves through the sky along with the stars. The higher the altitude (height) of the radiant, the more meteors you will be able see.
  3. Meteors enter Earth's atmosphere because Earth moves into the meteoroid cloud. This means that you will see more meteors when the spot on Earth where you are standing is facing the meteoroid cloud. This is always the direction in which the Earth is moving. If you are on the other side, the meteoroid cloud is 'behind' you and possible meteors will have to move faster than the Earth in order to enter the atmosphere. As pointed out by user Florin Andrei in the comments, this effect is also called the "bugs on the windshield" effect, because

Earth is like a car moving fast, and meteors are like insects that get splattered. Of course you get more bugs being splattered on the piece of glass that's facing forward.

Depending on your location, 1. and 2. could combine to maximise their effect some time before midnight. However, the effect of 3. is quite big. Because of the way the Earth rotates, this will always happen early in the morning, before sunrise.

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    $\begingroup$ Effect #3 is sometimes called the "bugs on the windshield" effect, because Earth is like a car moving fast, and meteors are like insects that get splattered. Of course you get more bugs being splattered on the piece of glass that's facing forward. $\endgroup$ – Florin Andrei Nov 16 '17 at 18:44
  • $\begingroup$ @FlorinAndrei I did not know that name, thank you :) and the analogy gives a nice visualization. I will include it in my answer. $\endgroup$ – Bart W Nov 16 '17 at 20:37

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