Astronomy - USA (2020-03)

WWW.ASTRONOMY.COM 21 erupting from Jupiter’s moon Europa. The plumes likely represent material from an underground ocean venting ...

22 ASTRONOMY • MARCH 2020 Now astronomers can observe f ledgling stars in gaseous nebulae as they emerge from their birth cocoon ...

WWW.ASTRONOMY.COM 23 to be far more complex than previously suspected. Instead of exhaling one dying breath, many Sun-like stars ...

24 ASTRONOMY • MARCH 2020 detail once possible only in the Milky Way. Black holes (almost) everywhere As Hubble cast its eye dee ...

WWW.ASTRONOMY.COM 25 get the expansion rate. Thirty years of Hubble observations have pinpointed the expan- sion rate at 73 kilo ...

26 ASTRONOMY • MARCH 2020 figure out how to bridge the gap. (See “Tension at the heart of cosmology” in the June 2019 issue.) Wh ...

WWW.ASTRONOMY.COM 27 It’s not surprising that galaxies collide frequently. After all, Hubble observa- tions show that the univer ...

28 ASTRONOMY • MARCH 2020 When astronomers look at large galaxy clusters, they often see wispy arcs and, sometimes, multiple ima ...

WWW.ASTRONOMY.COM 29 reaches around 1.4 solar masses, it explodes. Because type Ia supernovae arise from nearly identical progen ...

30 ASTRONOMY • MARCH 2020 How the Ritchey-Chrét J ust over 100 years ago, on October 31, 1919, George Willis Ritchey was fired f ...

Secondary mirror (hyperbolic) Eyepiece Primary mirror (hyperbolic) WWW.ASTRONOMY.COM 31 George Ritchey had great vision and skil ...

32 ASTRONOMY • MARCH 2020 hyperbolic secondary mirror at the Cassegrain focus were sharper than those taken with the same mirror ...

Secondary mirror (flat) Secondary mirror (hyperbolic) Eyepiece Eyepiece Eyepiece Incoming light Primary mirror (parabolic) Prima ...

34 ASTRONOMY • MARCH 2020 associations with the organization — he was deter- mined to create his own telescope-building company. ...

WWW.ASTRONOMY.COM 35 telescope maker. The French were more than happy to bid him adieu. Ritchey’s entire career in France had yi ...

SKY THIS MONTH Visible to the naked eye Visible with binoculars Visible with a telescope 36 ASTRONOMY • MARCH 2020 As we enter t ...

WWW.ASTRONOMY.COM 37 RISING MOON I A fortnight of features PACKED WITH DETAIL , the large crater Posidonius is near the top of m ...

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