What are comets, and why should we care about them? How have scientists studied them in the past, and how do they study them now? In this Text to Text, we pair an article from the Times archives about the then-cutting edge technology that allowed astronomers to photograph Halley's comet in 1910 with a recent Times article highlighting what astronomers hope to learn about the origins of the solar system from space-based observations of Comet ISON. Background: Comet ISON first made the news when a team of Russian astronomers spotted it in September 2012, and it garnered another flurry of attention in the spring and summer of 2013, with many referring to it as the "comet of the century." But comets, as the saying goes, are like cats: they have tails, and they do as they please. By late fall 2013, the comet took on a life of its own, fading and then disappearing from view, only to reappear. As of early December, the comet has all but disintegrated into a dust cloud, disappointing thousands who had hoped for a spectacular celestial holiday light show. A century earlier, in 1910, Halley's comet visited Earth's sky in a fly-by that was eagerly anticipated by scientists and the general public alike. The Times reported on the event with several front-page headlines, such as "Six Hours Tonight in the Comet's Tail" and "Comet Gazers See Flashes." Halley's comet is visible in the night sky every 76 years, and is due again in 2061. Key Questions: How has our understanding of comets changed with advances in technology over the last 100 years? Excerpt 1: "How Photography Helps Astronomy," Oct. 3, 1909 After pursuing its rapid flight in the boundless realms of space during the regulation period of about three-quarters of a century, at a velocity of something like a million miles per day - in other words, at the rate of once around our globe in a little over half an hour - it is announced that the great comment know as Halley's has once more made its appearance in the sky. For the moment, however, laymen need not excite themselves on the subject, for the famous wanderer is still so very far distant from the earth - not far short of 400 millions of miles - that neither with the naked eye nor even with powerful telescopes is it possible to detect the infinitesimally tiny speck. The ordinary reader will naturally ask, if this so, how has it been discovered that the meteor has returned? The explanation is simple enough. Scientific progress has revolutionized the method of taking astronomical observations as well as changing our views on other and more mundane matters. Photography has been substituted for the telescope when it is desired to discover a minute object in the realms beyond the sky. Astronomers use photographic plates especially devised for obtaining pictures of any selected space in the starry heavens, delicate clockwork arrangements keeping the plates on the move at precisely the same rate as the apparent movement of the stars, so that after an exposure of half an hour or more the stars are maintained at the same spots on the plate as the commencement of the operations. When developed, pictures obtained in this matter are found to disclose objects so far away from us that no telescope yet constructed is of the slightest use as an aid to observation. As the principal handmaid to astronomy, therefore, photography has become of immense importance, for the record is a permanent one, the details of which can be examined at leisure, whereas a view through a telescope is a passing one, and if an object is not noticed the particulars for that moment are lost.... Read entire article  Comet ISON's Trek Around the Sun. Video by NASA Excerpt 2: "Comet Nears Sun, Offering Planetary Clues," by Kenneth Chang A comet that spent the first 4.5 billion years of its existence in the farthest reaches of the solar system will almost graze the furnace of the sun on Thursday. Comet ISON's close approach - and its possible demise, from the sun's heat and gravitational forces - will give scientists an unprecedented look at the ingredients that came together to form the planets. "It's a dinosaur bone of solar system formation," said Carey M. Lisse, a senior research scientist at the Applied Physics Laboratory at Johns Hopkins University, during a NASA news conference on Tuesday. If the comet survives - though many experts like Dr. Lisse think it will not - it could provide a bright and striking addition to the night sky in early December as it zooms near Earth on its way back out. The best times for viewing would be right before sunrise or right after sunset. Currently it is not readily visible because it is too close to the sun.... For Writing or Discussion: How has technology changed in the time since Halley's comet came into view in 1909-10? How have these technological advances furthered our understanding of the nature of comets and the kinds of questions about the origins of the universe scientists are now able to ask and investigate? According to the first article, "Scientific progress has revolutionized the method of taking astronomical observations." What, in 1909, was this revolutionary method of observing objects in the sky? What kinds of observations did this technology make possible? What additional kinds of observations are possible with the technology available to scientists today? How did observations of Halley's comet with telescopes available in 1789 and 1836 differ from those made in 1909-10? Carey M. Lisse, a scientist quoted in the second piece, said of Comet ISON, "It's a dinosaur bone of solar system formation." What do you think he meant by this statement? What information about the early solar system do scientists hope to glean from Comet ISON, and how will they obtain this information? What interesting or amazing astronomical phenomena, such as comets, eclipses or shooting stars, have you observed in the night sky, either by using a telescope or with your naked eye? Describe. Going Further: Follow the Comets: Have students scour the Times archives for coverage of comets as early as the late 1800s. You might have them note when Halley's comet and the comets Shoemaker-Levy 9, Hale-Bopp and Hyakutake first came into view and compare the news coverage of these comets. When was each comet first sighted, and who spotted it? What kind of equipment, if any, was used? How did people respond to these comets? Students also could continue to follow the news about Comet ISON and what remains of it. Build a Model: Have students build a model of the solar system, including the Oort cloud and planetoids, showing the orbits of the planets and the trajectories of several of the comets that made the news in the past century. Explore the Myths: For centuries, comets have inspired not only awe and admiration but also fear and apprehension. Students might explore some of the cults, prophecies and other beliefs that have sprung up in response to comets. More recently, 39 members of a cult called Heaven's Gate participated in a mass suicide on the appearance of the Hale-Bopp comet in 1997. The members believed that the appearance of the Hale-Bopp comet was a sign that a U.F.O. was about to carry their spirits to another plane of existence. What might explain some of these superstitions? How, according to the first article, did Edmund Halley's calculation of the periodicity of Halley's comet help to quell some of these fears? Research the Latest Technology: What are some ways scientists are able to study comets today? How have they used orchestrated collisions and close-up photography to better understand the composition of comets? Will scientists be able to orbit a comet and land a probe on a comet's surface in 2014? Standards This resource may be used to address the academic standards listed below. Common Core E.L.A. Anchor Standards Reading 1 Read closely to determine what the text says explicitly and to make logical inferences from it; cite specific textual evidence when writing or speaking to support conclusions drawn from the text. 2 Determine central ideas or themes of a text and analyze their development; summarize the key supporting details and ideas. McREL Standards and Resources Science 3 Understands the composition and structure of the universe and the Earth's place in it.