The tidal forces generated by a black hole can be so powerful that they cause unlimited stretching, known as spaghettification. A detailed analysis of this phenomenon requires the use of Einstein's theory of general relativity. The aim of this paper is to offer an up-to-date and accessible analysis of spaghettification, in which the complex…

Given the great interest that black holes arouse among non-specialists, it is important to analyse misconceptions related to them. According to the author, the most common misconceptions are that: (1) black holes are formed from stellar collapse; (2) they are very massive; (3) they are very dense; (4) their gravity absorbs everything; and (5) they…

It often falls to a physicist to teach a conceptual astronomy course. It is easy to justify a treatment of general relativity in the context of massive stars, black holes, and cosmology. There are a number of good books available to serve as texts or references, including Thorne's "Black Holes and Time Warps: Einstein's Outrageous…

In 1974, Stephen Hawking theoretically discovered that black holes emit thermal radiation and have a characteristic temperature, known as the "Hawking temperature." The aim of this paper is to present a simple heuristic derivation of the Hawking temperature, based on the Heisenberg uncertainty principle. The result obtained coincides…

The ground-breaking image of a black hole's event horizon, which captured the public's attention and imagination in April 2019, was captured using the power of interferometry: many separate telescopes working together to observe the cosmos in incredible detail. Many recent astrophysical discoveries that have revolutionized the scientific…

The nature of light and how it is affected by gravity is discussed. Einstein's prediction of the deflection of light as it passes near the Sun was verified by observations made during the solar eclipse of 1919. Another prediction was that of gravitational redshift, which occurs when light emitted by a star loses energy in the gravitational field…

Trillion Theory (TT), a new theory, estimates the cosmic origin at one trillion years. This calculation of thousands of eons is based upon a growth factor where solar systems age-out at a max of 15 billion years, only to recycle into even larger solar systems, inside of ancient galaxies that are as old as 200 billion to 900 billion years. TT is a…

The Pulsar Search Collaboratory (PSC) engages high school students and teachers in analyzing real data from the Robert C. Byrd Green Bank Telescope for the purpose of discovering exotic stars called pulsars. These cosmic clocks can be used as a galactic-scale detector of gravitational waves, ripples in spacetime that have recently been directly…

Many concepts in astrophysics research can be difficult for a lay individual to understand or to comprehend their importance. One such example concept is the IceCube Neutrino Observatory, which detects high-energy neutrinos at the South Pole in Antarctica. The observatory uses information from detected neutrinos originating deep in outer space to…

A long time ago in a galaxy far, far away, two black holes, one of mass 36 solar masses and the other of mass 29 solar masses, were dancing their death waltz, leading to their coalescence and the emission of gravitational waves carrying away with them three solar masses of energy. More precisely, it happened 1.3 billion years ago at a distance of…

In 2015, the Smithsonian welcomed hundreds of thousands of people to the newly renovated Renwick Gallery (p. 6), their scientists peered to the edge of the black hole at the center of the Milky Way (p. 18), and their anthropologists helped identify the remains of leaders of the Jamestown colony (p. 28). The theme of this year's annual report is…

The problem of communication between observers in the vicinity of a black hole in a Schwarzschild metric is considered. The classic example of an infalling observer Alice and a static distant mother station (MS) is extended to include a second infalling observer Bob, who follows Alice in falling towards the event horizon. Kruskal coordinates are…

An introductory approach to black holes is presented along with astronomical observational data pertaining to the presence of a supermassive black hole at the center of our galaxy. Concepts of conservation of energy and Kepler's third law are employed so students can apply formulas from their physics class to determine the mass of the black hole…

The stars closest to Earth are not particularly remarkable or exciting. They are average stars typical of the spiral arms of our Milky Way galaxy. In fact, until recently, most astronomy and Earth science textbooks ignored all but the largest of them to focus on distant, more exotic objects like red supergiants or black holes. The recent discovery…

Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…