Question: Through Distant Worlds and Times was written by an astronomer whose first fundamental contribution to global science was what?

Through Distant Worlds and Times or Through Distant Worlds and Times: Letters from a Wayfarer in the Universe is a romantic scientific story written by Milutin Milanković, the Serbian mathematician, astronomer, geophysicist and climatologist, in the form of letters to an anonymous young woman. <SEP> Dr. Amy J. Barger (born January 18, 1971) is an American astronomer whose discoveries have most concerned quasars, black holes, and other far distant objects.  She helped show that the activity of black holes in nearby galaxies was greater and more recent than expected.  She also worked with others on discoveries concerning stellar activity in distant galaxies.  She currently is a professor at the University of Wisconsin–Madison. <SEP> Milutin Milanković (, pronounced ] ; 28 May 1879 – 12 December 1958) was a Serbian mathematician, astronomer, climatologist, geophysicist, civil engineer and popularizer of science.  Milanković gave two fundamental contributions to global science.  The second contribution is the explanation of Earth's long-term climate changes caused by changes in the position of the Earth in comparison to the Sun, now known as Milankovitch cycles.  This explained the ice ages occurring in the geological past of the Earth, as well as the climate changes on the Earth which can be expected in the future.  He founded planetary climatology by calculating temperatures of the upper layers of the Earth's atmosphere as well as the temperature conditions on planets of the inner Solar system, Mercury, Venus, Mars, and the Moon, as well as the depth of the atmosphere of the outer planets.  The first contribution is the "Canon of the Earth’s Insolation", which characterizes the climates of all the planets of the Solar system.  He demonstrated the interrelatedness of celestial mechanics and the Earth sciences, and enabled consistent transition from celestial mechanics to the Earth sciences and transformation of descriptive sciences into exact ones. <SEP> Extremes is the second book in the Retrieval Artist series by Kristine Kathryn Rusch.  The novels are situated at an unstated time in the future where humans have colonized many distant worlds.  In addition, treaties with alien races allow for the extradition of humans to other worlds to stand trial.  Since most of these extraspecies crimes carry a sentence of death, an industry has sprung up to hide these people.  Those who vanish are called the "Disappeared".  Not everyone who disappears does so to hide from aliens' justice, some are hiding from human justice, others just want to escape from their past.  Two professions have sprung up to find those people: Trackers and Retrieval Artists.  Trackers, similar to bounty hunters, seek the disappeared and return them to justice, or to those willing to pay for them to be found again.  Retrieval Artists also seek the disappeared, but instead of dragging them back to justice, are more often hired by lawyers seeking to have inheritances delivered (minus the sum it cost to find them).  Frequently, retrieval artist are followed by trackers in order to find the individual being sought.