Perhaps nothing stimulates the imagination quite the way that nebulae do.  The images produced by powerful modern telescopes atop mountains, in remote deserts, and stationed in space are often breathtaking in their beauty.  Their ethereal shapes and colors suggest earthly flora, fauna, and familiar objects such as roses and pelicans and hourglasses, and their clouds of dust and gas tell the histories of the stars that lit them up.

A Very Brief History

Observations of nebulae date back almost 2,000 years.  Early star-gazers stared intently at the night sky and noticed stars that seemed a little fuzzy to their unaided eyes.  In the second century C.E, Ptolemy noted five such “nebulous” stars.  Eight hundred years later, Abn al-Rahman al-Sufi mentioned “a little cloud” at the position where we now locate the Andromeda Galaxy.

Nicolas-Claude Fabri de Peiresc first observed the Orion Nebula through a telescope, in 1610. (Photo credit: ESO/Igor Chekalin)

The first to peer at a nebulous object through a telescope was Nicolas-Claude Fabri de Peiresc, in 1610, when he identified the Orion Nebula.  Christiaan Huygens apparently hadn’t heard of that discovery when he made the first detailed observations of the nebula, in 1659, thinking himself to be its discoverer.

There was a virtual avalanche of nebulae sightings in the 18th century by one astronomer after another, including luminaries Edmund Halley, Charles Messier, and William Herschel.  The number of identified nebulae grew rather quickly from six to 20 to 42 to 103 to over 2,000.

"Seeing is in some respect an art, which must be learnt."

-- William Herschel

It took more than another 100 years of study, debate, and technological advances before a consensus emerged, in the early 20th century, that many of the objects that appeared nebulous were, in fact, galaxies – and that true nebulae were actually clouds of gas and dust illuminated by the light of stars.

MyCn18 (aka the Hourglass Nebula) is a planetary nebula about 8,000 light years away. (Image credit: Raghvendra Sahai, John Trauger, the WFPC science team, and NASA/ESA)

Observing in the 21st Century

Viewing these endlessly fascinating objects in broad spectra of light, 21st century telescopes produce images that are startling in their clarity.  Thanks to the scientists and technicians who operate the Hubble Space Telescope and many other incredibly complex and sensitive instruments, we are privileged to see nebulae in all their majesty.  Their clouds are almost incomprehensibly vast, but they roil and billow and shape themselves into identifiable forms that we name and remember.  They are anything but nebulous.