In 1892, George Ellery Hale, a professor of astrophysics at the University of Chicago, convinced the university president to acquire two 40-inch telescope lens blanks. With funding from Charles Yerkes, a Chicago mass-transit tycoon looking to refurbish his image, Hale spearheaded the creation of an observatory to house the Great Refractor made with these blanks.Continue reading "Oct. 21, 1897: Yerkes Observatory is dedicated"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 20: Lovely spiral NGC 7331 The Orionid meteor shower peaks this morning — the perfect time to watch for shooting stars, as Earth turns into the meteoroid stream of dusty debris responsible for the show.  The best time to do someContinue reading "The Sky Today on Wednesday, October 21: Catch early-morning Orionids"

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Just as we use latitude and longitude to know the precise position of something on Earth’s surface, it’s useful to have a system for knowing the position of objects in the heavens. The widely used system of right ascension and declination does the job — and dates back at least to the time of HipparchusContinue reading "Understanding celestial coordinates"

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Few sights thrill backyard observers as much as the Orion Nebula (M42). The brightest stellar nursery visible from mid-northern latitudes resolves into a complex web of luminous gas and dusty tendrils even through modest telescopes. And at its core, you’ll see the brilliant young stars of the Trapezium Cluster that provide the energy to setContinue reading "JWST tours Orion’s hidden stellar nursery"

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BepiColombo, a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency, launched Oct. 20, 2018. The spacecraft is actually two satellites in one, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO), commissioned with investigating one of the least-visited planets in our solar system. To reach its final position,Continue reading "Oct. 20, 2018: BepiColombo launches"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 19: Feast your eyes on the Southern Fish Located in northern Pegasus, NGC 7331 is a bright galaxy that is the largest in a group of five galaxies collectively known as the Deer Lick Group. It’s best viewed in early evening,Continue reading "The Sky Today on Tuesday, October 20: Lovely spiral NGC 7331"

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Rocket launches this week On Monday, Oct. 19, the Japan Aerospace Exploration Agency (JAXA) successfully launched its Martian Moons eXploration (MMX) mission aboard an H3-24L rocket from Tanegashima Space Center in southern Japan at 3:41 p.m. EDT. MMX will study the martian moons Phobos and Deimos and is designed to return a sample from PhobosContinue reading "Japan sends MMX toward the martian moons"

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Sometime around the year 1837, a strange object passed an invisible cosmic mile marker: 1,000 astronomical units from the Sun. (One astronomical unit, or AU, is the average Earth-Sun distance.) For more than a century, it continued undetected toward our star. Finally, on Oct. 19, 2017, humans noticed the visitor. That night, a faint, thinContinue reading "Oct. 19, 2017: The discovery of ‘Oumuamua"

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Dave Doctor from Las Cruces, New Mexico The Hamburger Galaxy (NGC 3628) is an edge-on spiral in Leo, some 30 million light-years away, and a member of the Leo Triplet along with M65 and M66. Tidal interactions with those neighbors has extracted a faint tidal tail about 300,000 light-years long, part of which trails offContinue reading "A hamburger with a tail"

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On Oct. 4th, 1957, at 10:29 PM Moscow time, the Soviet Union successfully launched Sputnik 1 into space on a repurposed R-7 rocket. The world’s first artificial satellite, Sputnik was about 22 inches (58 centimeters) in diameter and weighed 184 pounds (84 kilograms). Although there were no scientific instruments aboard, the transmitter it carried sentContinue reading "Oct. 4th, 1957: Sputnik launches"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 3: Dione transits Saturn We’re back at Saturn this evening with the planet as the main attraction as the ringed world reaches opposition today at 8 A.M. EDT. Rising around sunset and setting around sunrise, it is visible all night inContinue reading "The Sky Today on Sunday, October 4: Saturn reaches opposition"

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A 12-ton rocket loaded with a 1-ton warhead, the V-2’s successful launch would prove to be exceptionally significant to both the military and to space exploration. On Oct. 3, 1942, the V-2 was fired from Peenemunde, Germany – its fourth test, and the first to succeed. The rocket rose to an altitude of 60 milesContinue reading "Oct. 3, 1942: The V-2 successfully launches"

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Huang Dandan, taken from Shennongjia, Hubei, China The gegenschein, a faint glow of sunlight scattered back toward Earth by dust grains in the inner solar system, sits in Aquarius at the point directly opposite the Sun in this all-sky view. The Milky Way arcs across the center, and the red light at bottom is aContinue reading "Gegenschein over Shennongjia"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 2: Venus stands still The small moon Dione transits Saturn starting just before midnight EDT. Tenth-magnitude Dione crosses the far northern region of the planet, beginning its journey just minutes after 11:40 P.M. EDT and taking about an hour and aContinue reading "The Sky Today on Saturday, October 3: Dione transits Saturn"

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If a train leaves the station in Exeter, England, headed south toward Newton Abbot five years before the railway line opens, how long until anyone figures out that it didn’t happen? Well, evidently about 155 years. A report on magnetic storms, published in Nature in 1871, described an incident thought to be the earliest recordedContinue reading "Case closed on long-standing space weather mystery"

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What type of lighting emits the least amount of light pollution? Peter BladoTacoma, Washington First, use a good lighting fixture, one that is a “full cutoff.” That means there is no direct upgoing light at all. It generally also means there is very little light just below the horizontal, which is the kind of lightContinue reading "How can I reduce my personal contribution to light pollution?"

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An ancient solar eclipse changed the course of a military conflict when it cast a shadow on a battle over Corinth between the Spartans, commanded by Cleombrotus, and the invading Persians, led by Xerxes I. Herodotus wrote that, “while [Cleombrotus] was offering sacrifice to know if he should march out against the Persians, the SunContinue reading "Oct. 2, 480 B.C.E.: A eclipse causes a retreat"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 1: Perseus’ Double Cluster The brilliant planet Venus stands stationary against the background stars of Virgo at 10 A.M. EDT.  Together with Mercury, Venus is visible for a short time in the western sky after sunset, but you’ll want a clearContinue reading "The Sky Today on Friday, October 2: Venus stands still"

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Looking for a sky event this week? Check out our full Sky This Week column.  September 16: Triangle in the sky The Moon passes 0.6° south of the bright star Antares at 9 A.M. EDT. By evening, our satellite sits near the border of Scorpius and Ophiuchus, some 6° east (to the upper left) of Antares. TheyContinue reading "The Sky Today on Thursday, September 17: The Moon and the Scorpion"

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Today I’ll be telling you about 10 of my favorite autumn deep-sky objects, with suggestions for viewing them. I hope you’ll enjoy this list, and I’ll share some other deep-sky favorites of mine from time to time in the future. What’s a large telescope? The notion of what’s big changes from observer to observer, butContinue reading "Autumn observing targets for large telescopes"

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