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leonids - Newest pictures Animals/Nature


Meteors (also known as "shooting stars") are thin streaks of light that are often seen in the night sky.
Meteors tend to be just a few millimeters across. Typically 2-5mm in diameter.
It's when these small particles are destroyed in the atmosphere (between 80-100km altitude) that we see them as shooting stars.
All of the major meteor showers (with one exception) originate from short period comets. As these comets enter the inner Solar System, they leave behind them streams of dusty particles and debris, which then orbits around the Sun.
There is just one shower which doesn't have a comet as its parent body. That is the "Geminids" meteor shower, which originates from an asteroid, "3200 Phaethon".
It's when the Earth encounters the streams of dusty particles and debris left behind by comets that showers ensue, occurring at the same time each year.
The image at the top of this page is of the Leonids meteor shower which occur at the same time each year, from 15th November until 20th November, when the Earth encounters the meteoroid stream laid down by Comet Temple-Tuttle.
Meteors from a shower emanate from a single point of the sky called the radiant, this is where the Earth encounters the meteoroid stream.
To determine where the radiant is, you simply have to visualize backwards where the meteors of a shower originate from. Meteors tend to shoot in all directions.
Meteor showers are named for the constellation which their radiant lies.
The Leonids, from Leo, Geminids, from Gemini, etc.
Sporadic meteors are not from a particular stream. They can appear all year round. They're random in their occupance. They originate from meteoroids swept up from the Zodiacal dust cloud (the general dusty background pervading the inner Solar System).
Meteoroid particles upwards of a few centimeters across, result in fireballs.
Fireballs are brighter than typical meteors. They often leave a brilliant stream behind them and can spectacular in appearance.
Random fireballs originate from chunks of interplanetary debris thrown into Earth-crossing orbits by collisions in the Asteroid Belt between Mars and Jupiter in the remote past.
The Zenithal Hourly Rate (ZHR) is the rate expected if the radiant were overhead. So, the predominant annual meteor showers and their ZHRs are as follows:

Quadrantids (radiant in Boötes) 1st-6th january, peaks on 4th jan. Maximum ZHR is 60.

Lyrids (parent comet- Thatcher), from 19th-25th april. Peaks on 21st, max ZHR is 10.

Eta Aqarids (parent comet- Halley), 24thapril-20th may. Peaks on 5th may. Max ZHR is 35.

Delta Aquarids, 15th july-6th august. Peaks on 29th july. Max ZHR is 20.

Perseids (parent comet is comet Swift-Tuttle), 23rd july-20th august. Peaks on 12th august. Max ZHR is 75.

Orionids (parent comet is Halley), 16th -27th october. Peaks on 22nd october. Max ZHR is 25.

Taurids (parent comet is Encke). 20th october-30th november. Peaks on 3rd november. Max ZHR is 10.

Leonids (parent comet is Tempel-Tuttle). 15th-20th november. Peaks on 17th. ZHR is variable.

Geminids (asteroid Phaethon is its parent body). 7th-16th December. Peaks on 13th December. Max ZHR is 75.

Ursids (parent comet is Tuttle). 17th-25th December. Peaks on 23rd december. ZHR is 5.

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