This graphic shows the radiant of the Perseid Meteor Shower and the orbit of the parent comet, Comet Swift-Tuttle, compared to the Earth.
(Image Sources: Wikipedia.org, By Aanderson@amherst.edu - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=41821851)
By Glenn A. Walsh
Reporting for SpaceWatchtower
This year's Perseid Meteor Shower,
which peaks late this week, is considered the best meteor shower of
the year by NASA and most astronomers.
Astronomically, the peak of the Perseid
Meteor Shower this year occurs Thursday Afternoon, 2021 August 12 at
3:00 p.m. Eastern Daylight Saving Time (EDT) / 19:00 Coordinated
Universal Time (UTC). However, the best time to watch most meteor
showers, including this year's Perseids, is always between local
midnight and dawn, when the Earth is rotating into the meteor shower.
So, the best time to view this year's
Perseid Meteor Shower is late Wednesday night / early Thursday
morning and late Thursday night / early Friday morning.
At the peak time, sometimes up-to
50-to-100 meteors could possibly be seen per-hour, if observing
conditions are ideal. Depending on your location, weather conditions,
and the condition of your eye-sight, seeing 40-to-60 meteors per-hour
would be more likely.
As most meteors are often dim, it is
best to view a meteor shower away from city lights, which cause a
brightening of the sky at night, and hence, the dimmest meteors are
often missed. And, you want to go out ahead of time, before you start
actual viewing of meteors, to get your eyes accustomed to the dark
sky. Dark-adapting your eyes for meteor watching could take up-to one
half-hour.
Also, after your eyes are dark-adapted,
do not look at your cellular telephone while looking for meteors. The
light you see from your telephone could disrupt your dark-adapted
night-vision.
For the Perseid Meteor Shower this
year, the Moon will be in a Waxing Crescent Phase, having passed the
primary lunar phase of New Moon four days earlier (Sunday, 2021
August 8 at 9:50 a.m. EDT / 13:50 UTC: Lunation #1220); the primary
Moon phase of First Quarter will occur on Sunday, 2021 August 15 at
11:19 a.m. EDT / 15:19 UTC. Although a thin lunar crescent will be
visible in the early evening, the Moon will set before local
midnight. Even during the early evening, there should not be quite as
much reflected sunlight from the Moon to obscure the dimmer meteors.
Try not to look directly at the Moon, so it does not hinder your
dark-adapted eye-sight.
Actually, some meteors from the Perseid
Meteor Shower can be seen as early as mid-July and as late as late
August (~July 17 to August 24); but they are few and far-between.
Most Perseid meteors can be seen three-to-five days before and
three-to-five days after the peak time, which is considered,
approximately, between August 9 and 14 each year.
Viewers in the Northern Hemisphere are
fortunate that the Perseid Meteor Shower arrives during the Summer
month of August, when temperatures are comfortable for night-time
viewing. However, some locations (such as in the mountains) could be
cooler in the early-morning hours. So, be sure to check your local
weather forecast (with NOAA Weather Radio, local forecasts on radio,
television or local newspapers, or the Internet) and bring a sweater
or jacket with you if your location has a cooler forecast.
Be aware that sometimes August can be
very humid with poor seeing conditions. And, the closer to the
horizon, the worse the seeing conditions could be.
Binoculars and telescopes are not very
useful for finding meteors. Meteors streak across the sky in a very
brief period of time, too short to aim binoculars or a telescope.
So, the best way to view a meteor shower is to lie on the ground
(perhaps on a blanket, sheet, or beach-towel—or possibly in a
reclining beach or lawn-chair), in an area with a good view of the
entire sky (with few obstructions such as buildings, trees or hills,
perhaps at a higher elevation), and keep scanning the entire sky with
your naked-eyes (one-power).
Meteor showers appear to emanate from
a radiant point in the sky. For the Perseid Meteor Shower, the
radiant appears to be within the Constellation Perseus, named for the
hero of Greek mythology (hence, the name Perseid Meteor Shower).
However, you should not, necessarily, be looking only at Perseus,
when looking for meteors in this shower.
Meteors can appear in any
part of the sky at any time. In fact, looking towards
Perseus may not result in finding the best meteors, as meteors coming
from the apparent radiant may be seen for a shorter time in the sky,
with much shorter sky streaks.
A meteor shower normally consists of
dust particles related to a comet. Each time a comet approaches the
Sun, the comet loses dust particles following the melting of ice on
the comet. These dust particles, called meteoroids, continue to
follow the same orbit as the comet and form a meteoroid stream. Each
year, as the Earth orbits the Sun, the Earth passes through several
of these meteoroid streams, becoming Earth's meteor showers.
The Earth's gravity then attracts many
of these meteoroids to fall to Earth, and they are viewed by people
as meteors, as they burn-up, often high in the atmosphere. Most are
extremely small and burn-up completely. From time-to-time, larger
particles enter the atmosphere and create brilliant displays known as
fire-balls or bolides. If these particles are large enough, they may
not completely burn-up and land on Earth as a meteorite.
Many museums and science centers display meteorites to the general public. From 1939 to 1991, the original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl Science Center - Pittsburgh's science and technology museum from 1939 to 1991) displayed the fifth largest fragment of the meteorite that formed Barringer Meteor Crater near Winslow, Arizona. This large meteorite is now displayed on the second floor of Pittsburgh's Carnegie Science Center, outside the entrance to the Henry Buhl, Jr. Planetarium. Meteorites are also on display in the Hillman Hall of Minerals and Gems at Pittsburgh's Carnegie Museum of Natural History.
Meteors can be seen any night of the
year, although they are not predictable and are rare outside of one
of the annual meteor showers. The vast majority of meteors that can
be seen during the Perseid Meteor Shower originate from Comet
Swift-Tuttle, which has an orbital period of 133 years, leaving
behind a trail of dust and grit. Comet Swift-Tuttle was discovered in
1862 and last returned for Earth viewing in 1992.
Comet Swift-Tuttle measures about 16
miles / 25 kilometers across, much larger than the object that is
thought to have fallen to Earth which resulted in the extinction of
the dinosaurs (about 6 miles / 10 kilometers across) approximately 66
million years ago (after the dinosaurs had lived on Earth for about
165 million years!).
Comet Swift-Tuttle will make a very
close approach to the Earth in the year A.D. 4479. Scientists are now
studying whether some day Comet Swift-Tuttle could impact the Earth.
Comet Swift–Tuttle has been described as "the single most
dangerous object known to humanity".
There are two additional meteor
showers, which both peaked at the end of July, with some meteors
still visible now.
The Southern Delta Aquariid meteor
shower peaked at 1:00 a.m. EDT / 5:00 UTC on July 29; these meteors
are visible each year between July 12 and August 23. It is not
certain which comet originated the Southern Delta Aquariids. This is
considered a strong meteor shower, with 15-to-20 meteors visible
per-hour, around the peak of shower; fewer would now be visible
per-hour.
The evening of July 29 / early-morning
of July 30 saw the peak of the Alpha Capracornid meteor shower. The
official peak occurred on July 30 at 2:00 a.m. EDT / 6:00 UTC. At the
peak time, five meteors per-hour are expected, making the Alpha
Capracornids a minor meteor shower; of course, now there would be
fewer Alpha Capracornids visible per-hour. The Alpha Capracornids,
which originated as remnants of Comet 169P / NEAT, are visible each
year from July 3 to August 15.
Another minor meteor shower may be
visible to some between August 28 and September 5; the peak is
expected August 31 / September 1. The Aurigid Meteor Shower is
believed to have originated as remnants of Comet Kless (C / 1911 N1).
Astronomers do not know the composition of this meteoric debris. So,
it is uncertain how the meteors from this shower may interact with
the Earth's atmosphere, and hence, scientists are unsure how visible
this shower may be each year.
So in mid-August, the time for viewing
is right, and the less moonlight is great. And, of course, with the
warm weather most of us experience in the Northern Hemisphere, this
time of year, what could be better for viewing meteors?
Of course, meteor showers, like all
celestial observations, are weather-permitting. Even a few clouds
could obscure quite a few meteors.
If the weather in your area does not
permit direct viewing of this meteor shower outdoors, it is possible
(but not guaranteed) you may be able to use Google, Yahoo, Bing,
Lycos, or your favorite Internet search engine to find special,
live-stream web-casts of the meteor shower at one or more sites on
the Internet.
A cautionary note for those who find it
necessary to watch the meteor shower on the Internet. The video
camera, used for each live-stream web-cast, can only aim at one part
of the sky at a time. Hence, do not expect to see as many meteors as
you might see with your own eyes outside. Outdoors, you can easily
scan the entire sky for meteors, while a camera aimed at one area of
the sky will only be able to see the meteors that enter that
particular field-of-view.
Internet Links to Additional Information ----
Perseid Meteor Shower: Link >>> https://en.wikipedia.org/wiki/Perseids
Comet Swift-Tuttle: Link >>> https://en.wikipedia.org/wiki/Comet_Swift%E2%80%93Tuttle
Constellation Perseus: Link >>> https://en.wikipedia.org/wiki/Perseus_%28constellation%29
South Delta Aquariid Meteor Shower: Link >>> https://en.wikipedia.org/wiki/Southern_Delta_Aquariids
Alpha Capracornid Meteor Shower: Link >>> https://en.wikipedia.org/wiki/Alpha_Capricornids
Aurigid Meteor Shower:
Link 1 >>> https://astronomyforbeginners.wordpress.com/2007/08/24/aurigid-meteor-shower-astronomy-for-beginners/
Link 2 >>> https://en.wikipedia.org/wiki/Aurigids
Meteor Shower: Link >>> https://en.wikipedia.org/wiki/Meteor_shower
Meteor: Link >>> https://en.wikipedia.org/wiki/Meteoroid#Meteor
Meteoroid: Link >>> https://en.wikipedia.org/wiki/Meteoroid
Meteorite: Link >>> https://en.wikipedia.org/wiki/Meteoroid#Meteorites
Fifth largest fragment of the meteorite which struck Barringer Meteor
Crater near Winslow, Arizona, which was displayed (1939 to 1991) at the
original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl
Science Center), Pittsburgh's science and technology museum from 1939 to
1991. Today, this meteorite is displayed on the second floor of
Pittsburgh's Carnegie Science Center, next to the Henry Buhl, Jr.
Planetarium:
Link >>> http://buhlplanetarium2.tripod.com/Buhlexhibits.htm#meteorite
Related Blog-Posts ---
Annual Perseid Meteor Shower Peaks Tue. Night / Early Wed. Morning." Mon., 2020 Aug. 10.
"Tonight's 'Meteor Outburst' w/Web-Casts: 150 Years After Comet-Meteor Shower Link Found." Thur., 2016 Aug. 11.
"Great Perseid Meteor Shower Peaks Wed. Night w/ Web-Casts." Wed., 2015 Aug. 12.
"Perseid Meteor Shower Peaks in Sky & Web-Casts." Tue., 2014 Aug. 12.
"Perseid Meteor Shower Peaks Sun., Mon. Nights." Sat., 2013 Aug. 10.
Source:
Glenn A. Walsh Reporting for SpaceWatchtower,
a project of Friends
of the Zeiss.
Monday, 2021 August 9.
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Glenn A. Walsh, Informal Science Educator &
Communicator:
Link >>> http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/
Electronic
Mail: < gawalsh@planetarium.cc >
Project
Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
SpaceWatchtower
Editor / Author: Link >>> http://spacewatchtower.blogspot.com/
Formerly
Astronomical Observatory Coordinator & Planetarium Lecturer,
original Buhl Planetarium & Institute of Popular Science (a.k.a.
Buhl Science Center), Pittsburgh's science & technology museum
from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library
and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author
of History Web Sites on the Internet --
* Buhl Planetarium,
Pittsburgh: Link >>> http://www.planetarium.cc Buhl Observatory: Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
*
Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
*
Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
*
Andrew Carnegie & Carnegie Libraries: Link >>> http://www.andrewcarnegie.cc
