Thursday, August 11, 2016

Tonight's 'Meteor Outburst' w/Web-Casts: 150 Years After Comet-Meteor Shower Link Found
Time-lapse image of the Meteor Outburst which occurred during the annual Perseid Meteor Shower in 2009. (Image Source: NASA / Jet Propulsion Laboratory)

By Glenn A. Walsh
Reporting for SpaceWatchtower

During tonight's peak of the annual Perseid Meteor Shower, NASA is predicting a possible “Meteor Outburst,” when 150-to-200 meteors per-hour might be visible under ideal conditions. Internet web-casts of this Shower / “Outburst” are available (Internet links to these web-casts are listed at the end of this blog-post), for areas which experience cloudy weather. This comes 150 years from the time that famous Italian astronomer Giovanni Schiaparelli discovered that comets are the cause of Meteor Showers.

This year's Perseid Meteor Shower and possible “Meteor Outburst,” which peaks tonight (Thursday Evening / Friday Morning), is expected to be one of the best of the last few years, due to no moon-light obscuring the dimmer meteors after moon-set. And, before the best viewing time period for the Meteor Shower / “Outburst,” a conjunction of the Moon, two planets, and a bright star are prominent.

“Forecasters are predicting a Perseid outburst this year with double normal rates on the night of Aug. 11-12,” said Bill Cooke with NASA’s Meteoroid Environments Office in Huntsville, Alabama. “Under perfect conditions, rates could soar to 200 meteors per hour.”

An “Outburst” is a Meteor Shower with many more meteors than usual. The last Perseid Outburst occurred in 2009. The next Perseid Meteor Outburst is expected around 2027.

After evening twilight in the southern sky on Thursday night, well before the best time to view the Meteor Shower, the waxing-gibbous Moon can be seen forming a quadrangle or diamond with the Planets Mars and Saturn, and the bright Star Antares (the Moon will be a little further to the left on Friday night). At about an hour after sun-set, Mars, appearing as a small red dot, can be seen below the Moon. Saturn can be seen to the lower left of the Moon, and Antares (Alpha Scorpii – the brightest star in the Constellation Scorpius the Scorpion, as well as the 15th brightest star in the night sky), also reddish, can be seen below Saturn and to the left of Mars.

The peak of the Perseid Meteor Shower, this year, actually occurs Friday Morning, 2016 August 12 at 9:00 a.m. Eastern Daylight Saving Time (EDT) / 13:00 Coordinated Universal Time (UTC). Since the peak time is closest to the early morning hours of Thursday Night / Friday Morning, this is considered the very best time to see Perseids. However, as the early morning hours of Friday Night / Saturday Morning are less than 24 hours after the peak, this time period may also feature a good share of Perseid Meteors.

This year, by around 2:00 local time both Friday and Saturday mornings, the waxing-gibbous Moon is setting or has set. The Moon had reached the First Quarter Phase yesterday, Wednesday Afternoon, 2016 August 10 at 2:21 p.m. EDT / 18:21 UTC. Bright moon-light, before moon-set, prevents the dimmer Perseid meteors from being seen. But once the Moon has set, more meteors can be seen, until astronomical twilight starts interfering with observing a little before dawn. So, looking for the many dimmer meteors which may be visible in the Meteor Outburst would be best after local moon-set.

During the peak time of most normal Perseid Meteor Showers, often 50 to 80 meteors can be seen per-hour, if observing conditions are ideal. As previously mentioned, NASA predicts the hourly rate of meteor visibility could be nearly doubled during the Meteor Outburst—again, under ideal observing conditions.

Well, what are ideal or perfect observing conditions? Ideal Meteor Shower observing conditions and viewing tips would include ---

                      Ideal Meteor Shower Observing Conditions & Viewing Tips
  1. Clear sky – Of course the sky has to be clear, or nearly clear, to be confident of viewing meteors.
  2. View meteors away from bright lights - 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.
  3. If possible, wait until after local moon-set – Due to the dark sky, our close Moon looks very bright in that sky, particularly when near the Full Moon phase. This bright light can also drown-out some of the dimmer meteors. So, it is best to wait until after local moon-set for meteor watching.
  4. Find a good observing site where the entire sky, or nearly the entire sky with a minimum of obstructions, is visible.
  5. Observe between, approximately, local midnight and local dawn - The best time to watch most Meteor Showers, when most meteors are entering Earth's atmosphere, is usually between local midnight and dawn, when the Earth is rotating into the Meteor Shower.
  6. Use your own  “one-power,” unaided eyes (i.e. naked-eyes) – Use your own eyes to scan the entire sky looking for meteors. 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 a beach towel or blanket on the ground, or sit in a reclining chair, in an area with a good view of the entire sky (with few obstructions such as buildings, trees or hills), and keep scanning the entire sky.
  7. Always scan the entire sky for meteors - Meteor Showers appear to emanate from a radiant point in the sky. As an example, for the well-known Perseid Meteor Shower, the radiant appears to be the Constellation Perseus, named for the hero of Greek mythology. 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.
  8. Go out to the night sky early, before you truly start observing, to adapt your eyes to the dark sky - Dark-adapting your eyes for meteor watching could take up to a half-hour.

Now, the information in the previous eight items are ideal Meteor Shower observing conditions and viewing tips, which would most likely result in the maximum meteors than could be observed. However, even if your conditions can not reach the ideal, so long as you follow these eight guidelines as close as possible, it is likely that you will see a fair number of meteors during a typical Meteor Shower.

Viewers in the Northern Hemisphere are fortunate that the Perseid Meteor Shower arrives during the Summer month of August, when temperatures are comfortable for nighttime viewing. Although, sometimes August can be very humid and muggy with poor seeing conditions.

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 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 fireballs or bolides. If these particles are large enough, they may not completely burn-up and land on Earth as a meteorite.

Most years, Earth might graze the edge of Comet Swift-Tuttle’s debris stream, the source of this well-known Meteor Shower, where there is less activity. Occasionally, though, Jupiter’s gravity tugs the huge network of dust trails closer, and Earth plows through closer to the middle, where there’s more material.

This may be one of those years. Experts at NASA and elsewhere agree that three or more streams are on a collision course with Earth.

“Here’s something to think about. The meteors you’ll see this year are from comet flybys that occurred hundreds if not thousands of years ago,” said NASA's Bill Cooke. “And they’ve traveled billions of miles before their kamikaze run into Earth’s atmosphere.”

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 the 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 returned for viewing in 1992.

Comet Swift-Tuttle measures about 16-miles across, much larger than the object that is thought to have fallen to Earth which resulted in the extinction of the dinosaurs. 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."

It was 150 years ago that famous Italian astronomer Giovanni Schiaparelli discovered that comets are the cause of Meteor Showers. Of course, Schiaparelli is best known for observing, what he called, “canali,” on the surface of Mars during the “Great Opposition” of Mars in 1877. In English, “canali” translates as channels. However, some people, particularly American businessman and amateur astronomer Percival Lowell, mistranslated the word to mean canals, giving the impression that such infrastructure may have been constructed by intelligent Martians.

In 1862, two American astronomers independently discovered (within three days of each other), what was originally designated Comet 1862III. Today, this rather famous comet is known by the name Swift-Tuttle, in honor of these two astronomers: Lewis Swift, his first comet discovery using a 4.5-inch refractor telescope, and Harvard College Observatory Astronomer Horace P. Tuttle, using the Observatory's 15-inch refractor telescope.

It was four years later, in 1866, when Schiaparelli matched the orbit of Comet Swift-Tuttle and the orbit he had previously plotted for the annual Perseid Meteor Shower. This was the first direct correlation between comets and Meteor Showers. The same year, he calculated the orbit of the Leonid Meteor Shower, and it was soon found that this orbit coincided with the orbit of the newly-discovered, but small, Comet Temple-Tuttle. From Schiaparelli's work, it was established that Meteor Showers came from comets.

So, the time for viewing is right and the lack of moon-light 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. If the weather in your area does not permit direct viewing outdoors of this Meteor Shower, it can be viewed during special web-casts on the Internet.

A cautionary note for those who find it necessary to watch the Perseid Meteor Shower on the Internet. The video camera, used for each 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 part of the sky.

Internet Sites for Viewing Perseid Meteor Shower Near Peak ---

Bareket Observatory, Israel - Aug. 11, 3:00 to 8:00 p.m. EDT / Aug. 11, 19:00 UTC to Aug. 12 0:00 UTC (Using CCD camera, which automatically refreshes):
Link >>>

Slooh Community Observatory - Aug. 11, 8:00 p.m. EDT / Aug. 12, 0:00 UTC:
Link >>>

NASA - BOTH on Aug. 11 and on Aug. 12 at 10:00 p.m. EDT / Aug. 12 and on Aug. 13 at 2:00 UTC: Link >>>

Internet Links to Additional Information ---

History of the Perseid Meteor Shower:
Link >>>

Perseid Meteor Shower: Link >>>

Comet Swift-Tuttle: Link >>>

Constellation Perseus: Link >>>

Meteor Shower: Link >>>

Meteor: Link >>>

Meteoroid: Link >>>

Meteorite: Link >>>

Fifth largest fragment of the meteorite which struck Barringer Meteor Crater near Winslow, Arizona, which was displayed at Pittsburgh's original Buhl Planetarium and Institute of Popular Science:
Link >>>

Related Blog Post ---


"NASA: Perseid Meteor Shower Has Most Fireballs." 2013 July 27.

Link >>>

Sources: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss; NASA.

             2016 Aug. 11.

                                                               Historic 10-inch Siderostat-type Refractor Telescope at Pittsburgh's original Buhl Planetarium and Institute of Popular Science.
        2016: 75th Year of Pittsburgh's Buhl Planetarium Observatory
     Link >>>

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