Photon Trajectories Encountering a Schwarzschild Black Hole
Here a plane wave of light encounters a non-rotating Schwarzschild black hole. Depending upon the impact parameter, the photons are either directly accreted by the black hole, captured into the black hole’s photon sphere, or gravitationally lensed and ejected on various trajectories.
Photon Trajectories Encountering a Kerr Black Hole
When a black hole is spinning, the resulting Kerr metric is much more complicated. Here a plane wave encounters a Kerr black hole rotating counterclockwise as seen from above. Gravitational frame dragging entrains the photons in the hole’s direction of rotation.
Here is more on the Coyote Buttes in northern Arizona and southern Utah. Within the area is a dinosaur trackway with more then 1000 footprints made by dinosaurs around 190 million years ago. The area shown in the picture is called “The Wave”, and made of eroded sandstone dating to the Jurassic period.
In Vienna, Austria, four retired coal gasgasometers (storage tanks) have been transformed into buildings containing apartments, offices, and commercial space. The buildings, officially opened in 2001, are named the Vienna Gasometers. Before conversion, each had a capacity of 90,000 metres³ of gas.
On the evening of 2024-01-18 Jupiter will appear close in the sky to the first quarter Moon, just a few lunar diameters (½°) away (3 or 4 degrees in the evening from North America). This will be a beautiful and photogenic sight, especially if you have a camera with a long focal length lens and tripod which can capture the discs of the Moon and Jupiter in the same frame. Since the Moon and Jupiter are currently the two brightest objects in the sky, you won’t need a long exposure so there’s no need for a guided camera platform. A longer exposure (or higher ISO setting on the camera) should be able to capture the moons of Jupiter stretched out in the plane of its equator (but will probably overexpose the Moon—that’s what composite images are for!). (The moons of Jupiter would be bright enough to be seen by the unaided eye in a dark sky if it weren’t for the glare of the giant planet.)
This will be the first of four close approaches of the Moon and Jupiter in January through April 2024. Here is a guide to observing them.
Astronomers Without Borders’ document, “Encounter of Jupiter and the Moon”, has more detailed information on observing and photographing the conjunction.
If you get any good photos, please post them here.
A conjunction of a bright planet with the Moon provides an excellent opportunity to spot the planet during broad daylight, which few people have ever done. Venus is bright enough to glimpse with the unaided eye (and the adjacent Moon makes it much easier by showing you where to look and providing a target upon which the eyes can focus.) See Fourmilab’s “Viewing Venus in Broad Daylight” for further information. Jupiter isn’t as bright as Venus, and I haven’t heard of anybody observing in full daylight with the naked eye, but it’s easy to spot with a telescope or binoculars if you know where to look, which the nearby Moon makes easy. As always, when using an optical instrument in daylight, take precautions not to accidentally sweep it past the Sun, which can blind you faster than your blink reflex. The safest way is to observe from a location shaded from the Sun, which also avoids glare that makes observation more difficult.
Fourmilab’s Your Sky will make a custom sky map for your location showing the position of the Moon and Jupiter. For example, here is the sky from my location in Switzerland at the time I posted this message (2024-01-18 at 15:48 UTC), when the Sun was approaching the horizon and the Moon and Jupiter were high in the southeast sky. None of this is apparent should I step outside into the drizzle and look up, thanks to typical Swiss weather in January. May you have better luck!
