Much as stars within galaxies tend to form within stellar clusters, the galaxies in the universe also tend to collect in groups, clusters, or even in a greater hierarchy of clusters of clusters, known as “superclusters.” Plots of galaxy positions versus redshift distance reveal the large-scale structure of the universe as a “cosmic web,” with galaxies lying along extended, thin “walls” and densely clustered intersections, surrounded by huge voids with few or no galaxies in between.

The close proximity of the Sun, and its extreme apparent brightness, makes it by far the most important star for lives here on Earth. In modern times we have access to powerful telescopes, both on the ground and in space, that observe and monitor the Sun over a wide range of wavelength bands. These vividly demonstrate that the Sun is, in fact, highly structured and variable over a wide range of spatial and temporal scales.

On the first Monday in October and continuing into late June or early July of the following year, the US Supreme Court sits in session. Unlike the executive and legislative branches of government, the day-to-day business of the Court is largely removed from public view. The nine justices who serve on the bench give interviews only sparingly, and television cameras are not allowed in the courtroom when hearings or deliberations are taking place. When appearing at formal public events, such as the annual State of the Union address given to Congress or the swearing in of a president, a justice is easy to spot because of his or her unusual attire – a black silk robe worn over a business suit.

The tendency for conservation of angular momentum of a gravitationally collapsing cloud to form a disk gives rise to the disk in our own Galaxy, the Milky Way. We explore the main components, including the disk, bulge, and halo. Studies of Galaxy rotation curves lead us to the existence of “dark matter,” the nature of which is unknown but is detectable through its gravitational interactions with normal, baryonic matter. We finish by exploring the supermassive black hole at the Milky Way’s center.

Let’s be clear: In Madison’s Republic, no one is really “in charge” since everyone – ordinary citizens and politicians alike – is just looking out for his or her own interests. And besides, everyone is effectively checked or frustrated by everyone else. What eventually emerges from the political process, then, is an amalgam of the interests in society, a kind of undirected free-for-all mish-mash of the range of interests engaged on any given policy question. However, in the clash of interests where politicians defend the interests of those who elected them in order to further their own interests in reelection, citizen-voters play a critical role.

Stars generally form in clusters from the gravitational contraction of a dense, cold giant molecular cloud. We explore the critical requirement for such contraction, known as the Jeans criterion, and the factors that affect the star formation rates and the initial mass function in star clusters and galaxies. We finish by looking at how the conservation of angular momentum can lead to proto-stellar disks, with important implications for forming planets.

To test which of these models applies to our universe, one needs to extend redshift measurements to large distances, out to several Giga-light years. The most successful approach has been to use white-dwarf supernovae (SN type Ia) as very luminous standard candles. One of the greatest surprises of modern astronomy is that the expansion of the universe must be accelerating! This implies there must be a positive, repulsive force that pushes galaxies apart, in opposition to gravity. We dub this force “dark energy.”