Messier Catalog

FIELDS OF STUDY: Extragalactic Astronomy; Historical Astronomy

ABSTRACT: French-born astronomer Charles Messier used telescopes to seek out comets in the Northern Hemisphere. He noticed other celestial objects in addition to the comets. These objects looked like blurs in the sky. To help astronomers identify these objects, Messier decided to categorize them. During his life, the astronomer classified more than one hundred objects in a catalog. The Messier Catalog became an important tool to astronomers and is still used in modern times.

Who Was Charles Messier?

Charles Messier was born in Salm, now part of the Lorraine region of France, on June 26, 1730. He was the tenth of twelve children born to Nicolas Messier and Françoise Grandblaise. Nicolas died when Messier was eleven years old, changing the dynamic and financial status of the family. An accident forced him to leave school and be tutored at home by his oldest brother. His brother taught him administrative, organizational, and observational skills, the latter of which served Messier well later in life.

Messier became interested in astronomy at a young age. Witnessing a solar eclipse in 1748 heightened this interest. In 1751 he began work with Joseph-Nicolas Delisle (1688–1768), the astronomer to the French Navy. Messier’s job was to keep records of space observations, and Delisle taught him how to measure exact positions of observations. Messier’s first documented observation was of the Mercury transit in 1753.

Messier became skilled at tracking astronomical objects such as comets, celestial bodies that form tails as they orbit the sun. While tracking comets in 1758, he noticed other astronomical objects that existed beyond the solar system. He later categorized these as deep-sky objects. Messier became a member of the Royal Society of London in 1764. He published the first edition of his catalog of deep-sky objects in 1771. Around that time, he was named astronomer to the French Navy. Messier continued to seek out comets and catalog deep-sky objects in the years that followed. At the time of his death on April 12, 1817, he had cataloged 103 Messier objects.

Classifying Deep-Sky Objects

Messier discovered deep-sky objects because of a mistake. In the late seventeenth century, English astronomer Edmond Halley (1656–1742) had examined historical records of comet sightings and cataloged his findings in A Synopsis of the Astronomy of Comets (1705). He found similarities between the orbits and parameters of three comet sightings in 1531, 1607, and 1682 and concluded that they were most likely the same comet returning to Earth every seventy-five or seventy-six years. Halley predicted the return of the same comet in 1758, but he died before he could see his prediction come true. The comet was later named Halley’s comet in his honor.

Messier began searching for the return of the comet around 1758, while he was working as an assistant to Delisle. However, Delisle made a mistake in his calculations, which led Messier to look in the wrong quadrant of the sky. While Messier was exploring the night sky in late August or early September 1758, he saw a fuzzy cloud between the stars of the Taurus constellation. He continued to study the blurry patch in the sky and determined that it did not move like the stars around it. This helped him rule it out as a comet. He determined that it was a nebula, or a cloud of gas and dust between the stars. Messier decided to catalog the astronomical object and named it Messier 1 (M1).

Messier continued to search for Halley’s comet using Delisle’s incorrect calculations. A German amateur astronomer, Johann Georg Palitzsch, spotted the comet on December 25, 1758. Messier used different calculations and eventually located Halley’s comet on his own nearly a month later.

Messier continued to add his and other astronomers’ findings to his journal, which became known as the Messier Catalog or Messier Album. The second entry, Messier 2 (M2), is a globular cluster that had been discovered by Italian astronomer Jean-Dominique Maraldi II (1709–88) in 1746. (A globular cluster is a near-spherical collection of old stars bound together by gravity.) Thereafter, Messier tasked himself with finding and recording deep-sky objects, or Messier objects as they came to be known. He said he undertook the project so that other astronomers would not mistake these objects for actual comets. Messier devoted himself to searching the night sky. By the time he died in 1817, he had cataloged 103 objects, 41 of which he had found himself. He also identified fifteen comets during his studies of the sky. Twelve of the comets bear his name.

Examples of Messier Objects

Most Messier objects appear faint and blurry. They typically cannot be seen without the aid of binoculars or a telescope. They are classified into several categories, including clusters, galaxies, nebulae, and supernova remnants.

The first recorded Messier object, M1, is a supernova remnant, left behind after the explosion of a star. It is more commonly known as the Crab Nebula. M3, located in the Canes Venatici constellation, is another globular cluster. M31, the Andromeda galaxy, is the closest galaxy to the Milky Way. M40 is a double star, or two stars that appear very close together when seen from Earth. M42, the Great Orion Nebula, is located in the Orion constellation. M45, the Pleiades, is an open cluster located in the Taurus constellation. An open cluster, also called a galactic cluster, is a group of same-aged stars within a cloud of dust and gas. M64, the Black Eye or Sleeping Beauty galaxy, is a spiral galaxy located in the Coma Berenices constellation. It has an area of dust that darkens its center.

Modern Relevance of the Messier Catalog

During the twentieth century, seven new Messier objects were added to the Messier Catalog, bringing the total to 110 objects. The final entry, M110, was recorded in 1967. It is a dwarf spherical galaxy found in the Andromeda constellation and a satellite galaxy of Andromeda galaxy.

Modern amateur astronomers still use the Messier Catalog to locate deep-sky objects in the Northern Hemisphere. Some even participate in the Messier Marathon, an event in which aspiring astronomers stay up to try to observe all 110 Messier objects in just one night. All that is needed is a pair of binoculars or a telescope and a clear night sky. The best time for viewing in the Northern Hemisphere is early March to early April.

Messier observed the sky from Paris, France, at a latitude of 49 degrees north. Consequently, people who do not have a northern vantage point cannot view all the Messier objects. For example, the objects M81 and M82 are at a declination of +69 degrees, which means that viewers below a latitude of 21 degrees south cannot see them above the horizon.

PRINCIPAL TERMS

• deep-sky object: a space object that exists beyond the solar system and cannot be seen with the naked eye.
• Messier object: an astronomical deep-sky object cataloged by French astronomer Charles Messier.

Bibliography

"Charles Messier (June 26, 1730–April 12, 1817)." Students for the Exploration and Development of Space. SEDS-USA, n.d. Web. 5 May 2015.

Dickinson, David. "Why This Weekend Is Perfect for a Messier Marathon." Universe Today. Fraser Cain, 5 Mar. 2013. Web. 5 May. 2015.

"Edmond Halley (1656–1742)." BBC History. BBC, 2014. Web. 7 May 2015.

"Explore the Night Sky, Hubble's Messier Catalog." NASA, 26 May 2022, www.nasa.gov/content/goddard/hubble-s-messier-catalog. Accessed 15 June 2022.

Gilmour, Jess K. The Practical Astronomer’s Deep-Sky Companion. London: Springer, 2003. Print.

Levy, David H., and Wendee Wallach-Levy. Cosmic Discoveries: The Wonders of Astronomy. New York: Prometheus, 2001. Print.

O’Meara, Stephen James. Deep-Sky Companions: The Messier Objects. 2nd ed. New York: Cambridge UP, 2014. Print.

Todd, Iain. "Messier Catalogue: The Complete List." BBC Sky at Night Magazine, 13 Sept. 2020, www.skyatnightmagazine.com/space-science/messier-catalogue/. Accessed 15 June 2020.