Globe at Night 2018 Leo Campaign Begins April 6 for Northern Latitudes

Summary: The Globe at Night 2018 Leo campaign begins Friday, April 6, and ends Sunday, April 15, for all northern latitudes.

Find Leo the Lion constellation by star-hopping from the Big Dipper asterism's pointer stars, Dubhe and Merak: Learn to Skywatch @Learntoskywatch, via Twitter March 22, 2017

The Globe at Night Leo campaign, which checks for light pollution effects on observing Leo the Lion constellation, begins Friday, April 6, and ends Sunday, April 15, for all northern latitudes.

The Globe at Night international citizen-science campaign’s website suggests that stargazing newcomers seek out Leo the Lion constellation by star-hopping from the Big Dipper asterism in Ursa Major (“Great Bear”) constellation. Dubhe (Alpha Ursae Majoris, α Ursae Majoris) and Merak (Beta Ursae Majoris, β Ursae Majoris), the two stars that mark the outer side of the Big Dipper’s bowl are known as pointer stars. Globe at Night explains that following the pointer stars to the north leads to the North Star, Polaris. A southward path from the pointer stars leads to Leo’s head.

A distinctive asterism, or pattern of stars, pinpoints Leo’s head. Known as the Sickle, the asterism looks like a backward question mark. Regulus (Alpha Leonis, α Leonis), the asterism’s brightest star, forms the question mark’s dot.

To the east of Regulus, at the opposite end of the constellation, is Denebola (Beta Leonis, β Leonis), the constellation’s second brightest star. Denebola (Arabic: danab al-asad, “tail of the lion”) anchors the tassel at the end of Leo’s tail.

Regulus and Denebola serve as guideposts for finding other stars in constellation Leo. Their stature as Leo’s two brightest stars are also helpful in assessing light pollution-induced skyglow.

EarthSky Tonight’s lead writer, Bruce McClure, describes the Northern Hemisphere’s spring months of late March, April and May as “superb months” for locating Leo the Lion constellation in the night sky. Leo’s northern spring visibility stretches from nightfall to the early morning hours.

Observers wait until more than an hour after sunset to conduct their assessment. Also, observations are made well before moonrise. Globe at Night suggests viewing between 8 and 10 p.m. local time.

Only five questions need to be answered by citizen scientist participants in the mid-spring Globe at Night 2018 Leo campaign. The first two required details concern time/date and location of observations. Globe at Night’s web app has an interactive tool that identifies latitude and longitude for place names.

The third question, “How dark was the sky that night?,” seeks magnitude details of the faintest visible stars at each observing location. Globe at Night’s seven magnitude charts image magnitudes that range from cloudy sky magnitude of less than 0.50 to star-filled sky magnitude of less than 7.50. Comparing the faintness or clarity of selected inter- and intra-constellation stars at the observer's location with the charts helps to establish the degree of light pollution-induced skyglow.

The fourth question concerns sky conditions, which affect visibility. Cloud cover estimates range from clear to coverages of one-quarter, one-half or more than half.

The fifth detail asks about use of a sky quality meter (SQM). The meter measures the brightness of the night sky in terms of magnitudes per square arcsecond.

Globe at Night targeted Leo the Lion constellation as an early spring 2018 northern constellation campaign. The early spring campaign ran from Thursday, March 8, through Saturday, March 17, for latitudes greater than 30 degrees.

In addition to 2018’s two Leo campaigns, Globe at Night has campaigns for eight other constellations in the Northern Hemisphere. Orion, Taurus and Gemini campaigns have already been completed. After Leo, Globe at Night is conducting campaigns centered on Bootes the Herdsman in May, Hercules the Hero in June and July, Cygnus the Swan in August and September, Pegasus the Winged Horse in October and Perseus the Hero in October, November and December.

Globe at Night’s 2018 Southern Hemisphere campaigns visit six constellations. Orion the Hunter and Canis Major campaigns have already been completed. Crux the Southern Cross campaign takes place in April, May and June. Scorpius the Scorpion campaign happens in July and August. The year’s two remaining Southern Hemisphere campaigns spotlight Sagittarius the Archer in September and October, and Grus the Crane in October, November and December.

The takeaway for the Globe at Night 2018 Leo campaign, which begins Friday, April 6, for northern latitudes, is that Leo the Lion constellation is one of nine constellations examined in 2018 by citizen scientists in the Northern Hemisphere for light pollution-induced skyglow.

Contact details for Globe at Night:

email: globeatnight@noao.edu
website: https://www.darksky.org

Globe at Night 2018 Leo campaign magnitude charts show Arcturus, brightest star in Bootes the Herdsman constellation, as visible on Magnitude 1 charts at latitudes 30 to 40 degrees north: AprilALearn to Skywatch @Learntoskywatch, via Twitter April 3, 2016

Acknowledgment

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

Image credits:

Find Leo the Lion constellation by star-hopping from the Big Dipper asterism's pointer stars, Dubhe and Merak: Learn to Skywatch @Learntoskywatch, via Twitter March 22, 2017, @ https://twitter.com/Learntoskywatch/status/844609664046317573

Globe at Night 2018 Leo campaign magnitude charts show Arcturus, brightest star in Bootes the Herdsman constellation, as visible on Magnitude 1 charts for latitudes 30 to 50 degrees north: Learn to Skywatch @Learntoskywatch, via Twitter April 3, 2016, @ https://twitter.com/Learntoskywatch/status/716686921892818944

For further information:

The Astronomical League. "Navigating the April Night Sky, Northern Hemisphere."Astronomers Without Borders > All Sky Map.
Available @ https://www.astronomerswithoutborders.org/docs/AllSkyMap2.pdf

“Can You Find Leo?” Globe at Night > Finding Constellations.
Available @ https://www.globeatnight.org/finding/leo

Fazekas, Andrew. “GLOBE at Night -- Helping to Save the Night Sky.” National Geographic Blog > Changing Planet. Jan. 20, 2012.
Available @ https://blog.nationalgeographic.org/2012/01/20/globe-at-night-helping-to-save-the-night-sky/

Learn to Skywatch @Learntoskywatch. "Tonight's Target: Can you find the constellation "Coma Berenices"? Hint: Use Leo and the Big Dipper to locate it." Twitter. April 3, 2016.
Available @ https://twitter.com/Learntoskywatch/status/716686921892818944

Learn to Skywatch @Learntoskywatch. "Tonight's Target: The Lion's Mane Can you find "The Sickle" in the constellation Leo? Hint: The Big Dipper points the way." Twitter. March 22, 2017.
Available @ https://twitter.com/Learntoskywatch/status/844609664046317573

McClure, Bruce. “Leo? Here’s Your Constellation.” EarthSky > Constellations. April 15, 2017.
Available @ http://earthsky.org/constellations/leo-heres-your-constellation/