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Stargazing to Star Charts: Engaging Students in the Wonders of Astronomy

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APOD:Gum 37 and the Southern Tadpoles
Image Credit & Copyright: Francis Bozon & Cecil Navick (AstroA. R. O.)

Explanation: This cosmic skyscape features glowing gas and dark dust clouds alongside the young stars of NGC 3572. A beautiful emission nebula and star cluster, it sails far southern skies within the nautical constellation Carina. Stars from NGC 3572 are toward top center in the telescopic frame that would measure about 100 light-years across at the cluster's estimated distance of 9,000 light-years. The visible interstellar gas and dust, shown in colors of the Hubble palette, is part of the star cluster's natal molecular cloud, itself cataloged as Gum 37. Dense streamers of material within the nebula, eroded by stellar winds and radiation, clearly trail away from the energetic young stars. They are likely sites of ongoing star formation with shapes reminiscent of the Tadpoles of IC 410 -- better known to northern skygazers. In the coming tens to hundreds of millions of years, gas and stars in the cluster will be dispersed though, by gravitational tides and by violent supernova explosions that end the short lives of the massive cluster stars.

APOD:Saturn's Rings Appear to Disappear
Image Credit & Copyright: Natan Fontes

Explanation: Where are Saturn's ears? Galileo is credited, in 1610, as the first person to see Saturn's rings. Testing out Lipperhey's recently co-invented telescope, Galileo did not know what they were and so called them "ears". The mystery deepened in 1612, when Saturn's ears mysteriously disappeared. Today we know exactly what happened: from the perspective of the Earth, Saturn's rings had become too thin to see. The same drama plays out every 15 years because Saturn, like Earth, undergoes tilt-driven seasons. This means that as Saturn goes around the Sun, its equator and rings can tilt noticeably toward the Sun and inner Solar System, making them easily visible, but from other orbital locations will appear almost not at all. The featured picture from Brasilia, Brazil shows a modern version of this sequence: the top ring-dominated image was taken in 2020, while the bottom ring-obscure image taken earlier in 2025.

APOD:Spin up of a Supermassive Black Hole
Illustration Credit: Robert Hurt, NASA/JPL-Caltech

Explanation: How fast can a black hole spin? If any object made of regular matter spins too fast -- it breaks apart. But a black hole might not be able to break apart -- and its maximum spin rate is really unknown. Theorists usually model rapidly rotating black holes with the Kerr solution to Einstein's General Theory of Relativity, which predicts several amazing and unusual things. Perhaps its most easily testable prediction, though, is that matter entering a maximally rotating black hole should be last seen orbiting at near the speed of light, as seen from far away. This prediction was tested by NASA's NuSTAR and ESA's XMM satellites by observing the supermassive black hole at the center of spiral galaxy NGC 1365. The near light-speed limit was confirmed by measuring the heating and spectral line broadening of nuclear emissions at the inner edge of the surrounding accretion disk. Pictured here is an artist's illustration depicting an accretion disk of normal matter swirling around a black hole, with a jet emanating from the top. Since matter randomly falling into the black hole should not spin up a black hole this much, the NuSTAR and XMM measurements also validate the existence of the surrounding accretion disk.