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Northern Rockies Skies for June: Draco the Dragon
A monthly look at the night skies of the northern Rocky Mountains, written by astronomers Ron Canterna, University of Wyoming; Jay Norris, Challis, Idaho Observatory; and Daryl Macomb, Boise State University.
Draco the Dragon can be seen winding its way between the Big and Little Dippers (Ursa Majoris and Ursa Minoris) and the constellations Cepheus, Cygnus, Lyra and Hercules in the northern celestial hemisphere. Although it is the eighth largest constellation in the sky, its stars are quite modest in brightness, which makes this constellation sometimes difficult to locate.
From Greek mythology, Draco guarded the golden apples of Hera. It was one of the 12 labors of Hercules to steal a golden apple as Draco guarded them.
June Planet Alert: Right after sunset toward the west you will see Jupiter sinking below the horizon. Mars is in Virgo this month and Saturn is seen in Libra between the stars Spica and Antares. Venus is the morning star this month.
The summer solstice is June 21, so welcome summer. We badly need it.
Interest: The Flatness Problem
(Best URL: http://en.wikipedia.org/wiki/Flatness_problem)
Portrayals of curvature in the universe represent the concept of dense regions of matter "curving" the fabric of spacetime. The popular picture is that of a black hole being so dense as to make light paths passing close to the hole deviate from a straight line, orbit the hole, or the light's trajectory being inescapably drawn into the hole by its intense gravity.
On large scales of clusters of galaxies, imperfectly "lensed" light paths of even more distant galaxies are often seen as multiple images in some photographs taken by the Hubble Space Telescope. This effect is called gravitational lensing.
However, on the very largest scale of the observable universe (billions of light-years), the available data show that the small deviations of light paths as occur in gravitational lenses average out to zero: the universe is "flat,” not curved. The average density of matter is such that the universe will not eventually collapse, it is not positively-curved or "closed" nor is it negatively-curved or "open."
Further, from earlier times in the universe's expansion, it can be shown that any curvature was infinitesimally small, effectively zero. This issue, first noticed in 1969 by the physicist Robert Dicke, is known as "the flatness problem" -- one of the so-called cosmological fine-tuning problems. The question is, how did the universe come to be so close to flat, given the apparently large range of possible average densities and, therefore, possible curvatures?
Before the current expansion phase, an inflation phase (lasting a small fraction of a second) during the very early universe has been suggested that "inflates" its size exponentially rapidly, giving rise to an extremely flat spacetime. (Inflation also is postulated to solve the horizon problem, discussed last month.)
Recently, results from Planck satellite observations -- which very accurately measured the radiation signature of the cosmic microwave background -- provided evidence supporting inflation scenarios, although the detailed physics of what caused inflation remain almost completely unelaborated. One profound consequence of the inflation phase and the resulting flat universe would be that the fraction observable by us on Earth, or in fact from any point, is very small: the entire universe would be enormously larger, by at least 60 powers of 10, than the portion we can observe.
To view this month’s sky chart, click here.