2018 Lyrid Meteor Shower Peaks Before Dawn Earth Day, Sunday, April 22

Summary: The 2018 Lyrid meteor shower peaks before dawn Earth Day, Sunday, April 22, but surrounding dates of April 21 and 23 also offer great shower views.

Lyrid meteor shower’s radiant point is near Alpha Lyrae, known as Vega, the brightest star in Lyra the Harp constellation: Bruce McClure and Joni Hall/EarthSky, CC BY SA 3.0 Unported, via Wikimedia Commons

The 2018 Lyrid meteor shower peaks before dawn Earth Day, Sunday, April 22, but great shower views are also possible on the surrounding dates of Saturday, April 21, and Monday, April 23.

Earth’s moon cooperates with visibility of the 2018 Lyrid meteor shower’s peak dates. Saturday’s waxing crescent has approximately 35 percent illumination. The first quarter phases takes over Sunday, April 22, at 21:46 Coordinated Universal Time (5:46 p.m. Eastern Daylight Time). Moonsets occur on all three dates prior to peak viewing hours.

Meteor showers usually derive their name from the constellation from which their meteors appear to originate. The parallel, same-velocity path traveled by a meteor shower’s particles seems, to an observer, to trace back to a single point in the sky.

The point from which meteor shower particles apparently radiate is known as the radiant. The radiant point is actually an illusory effect of perspective, by which eyes interpret parallel objects as converging at a far point or horizon line.

April’s Lyrid meteor shower is named after Lyra the Harp. The Lyrids’ shooting stars have an apparent radiant in proximity to Alpha Lyrae (α Lyr, α Lyrae), the constellation’s brightest star.

Vega is Alphae Lyrae’s popular name. Vega anchors the easternmost angle of the inverted triangle that perches atop Lyra the Harp’s parallelogram.

Vega participates in the Summer Triangle. The inter-, or multi-, constellation asterism comprises Altair (Alpha Aquilae, α Aquilae), Deneb (Alpha Cygni, α Cygni) and Vega, the brightest stars in Aquila the Eagle, Cygnus the Swan and Lyra the Harp, respectively.

Best viewing of the Lyrid meteor shower happens in the Northern Hemisphere. Vega’s location equates to more than 38 degrees north of the imaginary celestial equator that astronomers helpfully project from Earth’s equator outward into space.

EarthSky Tonight’s lead writer, Bruce McClure, explains that, around the Lyrid meteor shower’s maximum, Vega rises above the northeast horizon around 9 or 10 p.m. local time for mid-northern latitudes. Vega’s upward climb is high enough by midnight local time for northern observers to notice Lyrid shooting stars. Before dawn, Vega’s high overhead placement in the northeast-east sky allows for maximum Lyrid visibility, at approximately 10 to 20 meteors per hour.

The American Meteor Society describes the Lyrid meteor shower as a “medium strength shower,” with particle velocity at 30 miles per second (48.4 kilometers per second). Peak zenithal hourly rate (ZHR) of 18 meteors per hour may occur when the radiant is at its zenith, or highest point.

Southern Hemisphere Lyrid seekers in the mid-southern latitudes have viewing possibilities between midnight and dawn. On his Meteor Showers Online website, American amateur astronomer Gary W. Kronk places the radiant in the north-northeast sky. The hourly rate will be lower because Vega perches lower in the Southern Hemisphere skies than in Northern Hemisphere skies.

The annual Lyrid meteor shower, also known as the Lyrids or the April Lyrids, generally shoots meteors between April 16 and April 26. Gary Kronk notes via Meteor Showers Online that British amateur astronomer William Frederick Denning (Nov. 25, 1848-June 9, 1931) observed weak Lyrid activity as early as April 14 annually. Czech-born American astronomer Zdenek Sekanina (born June 12, 1936) indicates that the Harvard Radio Meteor Project, conducted 1961 to 1965 at Havana, Mason County, west central Illinois, detected possible annual Lyrid stream activity as late as May 3.

Earth’s passage through cometary debris causes meteor showers. The Lyrid meteor shower’s parent body is comet C/1861 G1 (Thatcher). NASA’s Solar System Exploration website demystifies comet Thatcher’s alphanumeric prefix. The letter “C” indicates a long period comet, with an orbital period of 200 years or more. Comet Thatcher’s completes an orbit of the sun approximately every 415.5 years.

The number “1861” indicates the year of discovery. The letter “G” represents the first half of April. The number “1” tells that Thatcher was the first cometary discovery during the half-month period.

American amateur astronomer Albert E. Thatcher is credited with discovering his namesake comet in the year of the long period comet’s perihelion, or closest approach, to the sun. Thatcher made his discovery via Columbia University's Rutherford Observatory. His New York City-based discovery Thursday, April 4, 1861, preceded an independent discovery Sunday, April 28, 1861, by Carl Wilhelm Baeker in Nauen, Brandenburg state, northeastern Germany.

The takeaway for the 2018 Lyrid meteor shower’s peak before dawn Earth Day, Sunday, April 22, is that the moon’s waxing crescent April 21 and first quarter April 22 and 23 will have vacated northern skies before peak viewing.

Lyrid meteors and the Milky Way; near Lake Tahoe, Hope Valley, California; April 22, 2013; photo by Mark Lissick/Wildlight Nature Photography: Fox Astronautics @FXAstronautics, via Twitter Jan. 23, 2018

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Lyrid meteor shower’s radiant point is near Alpha Lyrae, known as Vega, the brightest star in Lyra the Harp constellation: Bruce McClure and Joni Hall/EarthSky, CC BY SA 3.0 Unported, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Lyrid_meteor_shower_radiant_point.jpeg

Lyrid meteors and the Milky Way; near Lake Tahoe, Hope Valley, California; April 22, 2013; photo by Mark Lissick/Wildlight Nature Photography: Fox Astronautics @FXAstronautics, via Twitter Jan. 23, 2018, @ https://twitter.com/FXAstronautics/status/955914573646712832

For further information:

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Available @ https://twitter.com/FXAstronautics/status/955914573646712832

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Available via HathiTrust @ https://hdl.handle.net/2027/nyp.33433066362348?urlappend=%3Bseq=223

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