Watch your sky

For all I know, the dinosaurs did apparently not have much interest in looking at the sky. Also, they did not seem to have any capability that would have led them to plan ahead in detail. The major part of their activities likely were to hunt down other species for food. It was a successful life philosophy; dinosaurs were wide-spread on Earth for more than 200 million years. Among their hunted, there were some which fed milk to their offspring, the mammals. Because they were quite small, mammals would have been an easy target for the dinosaurs. Probably because they were under almost constant threats, mammal species evolved into various types, and because they were much threatened, many likely built their living quarters in protective places. They would have to have been acutely aware of their surroundings, both on the ground, and above and below. Anticipation of danger would have been an important characteristic. Altogether, mammals would have become very flexible, in order to stay alive.

These two different "philosophies of life" eventually cost the dinosaurs their existence, except for one or two who became the ancestors of our current species of birds. The mammals' approach to living insured the survival of at least some primate-like mammalian species. The main cause for this turn of events was very likely the impact of an extremely large meteorite, which 66 million years ago or so caused world-wide destruction of plants and animals on land, in oceans and lakes, and also caused extreme changes in the atmosphere. The Chicxulub crater located on the Golf of Mexico's Yucatán peninsula is believed to be the remnant of this catastrophic event.

Some primate species turned into the human line about 3 million or so years ago and today, we are spread around the world. Our "smarts" have increased to an amazing level (although I wonder sometimes, considering the current political conditions, and the disregard for past warnings of a major climate change ahead). The most impressive aspect for me is our capability to travel in space. 

As a prime requisite this requires technologies to obtain a very accurate knowledge of the effects of gravity, astronomical distances, and ongoing precise measurements and observations, the mathematics to precisely calculate orbits, and intense observations of the space environment. If we want to avoid another Chicxulub, then among these ongoing activities is the necessity of looking out for large Near Earth Objects, whose orbit might lead them to a serious collision with the Earth. Fortunately, a fair number of organizations do this; NASA is leading the way. We also need to build up the capability to alter the orbit of any such threatening object, so that it will bypass us. 

The first test to alter the orbit of an NEO has already been completed successfully. NASA put out a press release about its Double Asteroid Redirection Test, an attempt to hit the "moon" of NEO Didymos, called Dimorphos. 

Here is an excerpt from the press release:  

“All of us have a responsibility to protect our home planet. After all, it’s the only one we have,” said NASA Administrator Bill Nelson. “This mission shows that NASA is trying to be ready for whatever the universe throws at us. NASA has proven we are serious as a defender of the planet. This is a watershed moment for planetary defense and all of humanity, demonstrating commitment from NASA's exceptional team and partners from around the world.”

Prior to DART’s impact, it took Dimorphos 11 hours and 55 minutes to orbit its larger parent asteroid, Didymos. Since DART’s intentional collision with Dimorphos on Sept. 26, astronomers have been using telescopes on Earth to measure how much that time has changed. Now, the investigation team has confirmed the spacecraft’s impact altered Dimorphos’ orbit around Didymos by 32 minutes, shortening the 11 hour and 55-minute orbit to 11 hours and 23 minutes. This measurement has a margin of uncertainty of approximately plus or minus 2 minutes.

Before its encounter, NASA had defined a minimum successful orbit period change of Dimorphos as change of 73 seconds or more. This early data show DART surpassed this minimum benchmark by more than 25 times.  

This imagery from NASA’s Hubble Space Telescope from Oct. 8, 2022, shows the debris blasted from the surface of Dimorphos 285 hours after the asteroid was intentionally impacted by NASA’s DART spacecraft on Sept. 26. The shape of that tail has changed over time. Scientists are continuing to study this material and how it moves in space, in order to better understand the asteroid.

Credits: NASA/ESA/STScI/Hubble

One must call this a major achievement on the way to protect Earth from a catastrophe similar to which befell the dinosaurs. However, we can't just consider the fate of our Earth. We have the benefit if a fairly dense atmosphere, which not only keeps us alive, but also does a pretty good job of protecting us from the meteors which hit us every day and night. Those range in size from dust grains to small asteroids and burn up in the air because of their high speed (think of shooting stars and fireballs). Beyond a certain size they do not burn up: the bigger, the worse.

There are projects underway which propose human visits to, and settlements on our Moon and also Mars. The threat of meteorite impacts exists for them just as much as it does for us. It is danger enough; but another threat exists pursuing these plans: highly ionized space radiation. Our atmosphere, and Earth's magnetic field, do a reasonable job of protecting us against this radiation too. That is not quite the case on the Moon and Mars.

So, using all possible methods: Watch Your Sky...

An experiment

In the late 1980s, my wife and I moved to Toronto for a limited time. During our stay there (about 3 1/2 years) I joined the RASC Toronto Centre, but I also kept my membership in the Vancouver Centre. The Toronto Centre also has a group of people who observe the sky actively. Just as here in Vancouver, light pollution problems in the city made us look for a darker sky, but within a reasonable driving distance. During fall and winter, clear nights in Ontario can be very cold, so you have to be prepared to have some related effects on your telescopes (and yourself - dress accordingly).

Occasionally, cold air's low relative humidity will fog up your telescope's lenses' external surfaces. Since wiping them by hand is always a bit chancy, some "no-touch" method is preferred. That usually requires some electric power supply to run a "gentle" warming fan or use some other warming method to clear the lenses. In general, that means fairly large, portable batteries, or a connection to your vehicle, or gasoline-driven generators. These requirements made me try another approach. 

Many telescopes come with "dew caps", meant to counter the fogging of optics. I own a C-8 telescope, whose performance and portability make it ideal for observing at various locations. My C-8 did not come with a dew cap, but I found one labelled as made by Nova Astronomy-Products in Toronto. It fit the C-8 nicely. Since my working activities involved electronics, I thought of trying a simple experiment involving standard, small sized resistors (1 to 2 watt rated) to come up with a low powered warming system to repel some more humidity. 

I decided to use 5 resistors with a heat rating of 2 Watts and a resistance of 15 Ohms each (mainly because I had them on hand) and taped this series of resistors into the dew cap so that the resistors are placed near the front of the C-8 when the dew cap is attached to the C-8. The amount of heat generated is small. If you apply 12 Volts to the resistor series (Total of 75 Ohms resistance) you'll get slightly less than 2 Watts as the total amount of heat generated. Each resistor contributes a little less than 0.4 Watts.

One caution: If you double applied voltage, you will get four times the heat, four times the voltage gives you sixteen times the heat. Remember that the resistors I used can handle only a maximum of 2 Watts each. The effects of Voltage and electrical current changes occur in the domain of the square of their original values. You can exceed ratings and do damage very quickly. Stick with your original values.

 

The black dew cap mounted on the front end of the orange C8 telescope. The 5 resistors are attached inside the dew cap, where the dew cap and telescope meet.

Inside the dew cap, one of the 15 Ohm, 2 Watt, resistors is shown in front of the C8. Held in place by a small piece of Velcro.

Note  the 5 resistors deep in the C-8 dew cap, just in front of the C-8 telescope. They are connected as a series circuit. You can see the wire which connects one to the next. The resistors do not touch the C-8 telescope.

The 2 wires for connecting the resistors to the external voltage source are a small bundle at the lower left, on top of the tripod telescope mount.

You may want to try something similar to what is described above. The "small scale" warm-up arrangement worked reasonably well (and is still, more than 30 years later) at moderate humidity levels. It requires very little electrical power, so that there is little demand on a battery used for powering other functions on your telescope. 

Life as we know it

 Last Christmas, I received a present from my family, a book by David Attenborough titled "Living Planet, The Web of Life on Earth". The book was chosen by my granddaughter Meredith. She is in her last year of Marine Biology studies at SFU; obviously, the book relates to that.

There are a number of picture plate sections distributed throughout the book. Among them are excellent images of "black smokers", located about 3km below ocean surface, which exude hot, sulphide-laden water, and are the home of several anaerobic species (no sunlight). None-the-less, they are a form of life "as we know it"; they are still DNA-based.

 

A black smoker (From Wikimedia Commons, the free media repository)

Here's a quote from https://theliquidearth.org/2010/10/black-smokers: Black smokers are black chimney shaped formations that are found in large numbers in “hydrothermal vent fields” in the abyssal and hadal zones of the world’s oceans.  The fields are hundreds of meters wide usually found where tectonic plates below the ocean are moving, where water seeps down into the rocks where it becomes superheated, before returning to the surface where it clouds on contact with the cold ocean water due to the abundance of dissolved minerals in it.  On contact with the cold water, these minerals fall back to the ocean floor forming a chimney structure around the vent.  Because of the large amount of sulphides in the superheated water, sulphide ore deposits are usually found at the base of each chimney. Water at the bottom of the ocean is only around 2^oc, the water escaping the chimney of the black smoker can be as high as 400^oc (end of quote).

This made me think of the efforts currently being initiated by NASA to send a probe to Europa, the second closest Galilean moon orbiting Jupiter. The name of the probe is Europa Clipper. Fly-bys by an earlier probe (called Galileo) notwithstanding, there's still relatively little known about Europa. This new, in-progress mission, NASA hopes, is going to improve our understanding of that moon. As is quite common, the underlying reason is our search for evidence of possible life elsewhere, other than on Earth. The plan is to launch the probe into space by 2024 to extensively explore Europa from space after arrival in 2031. This multi-orbit exploration will employ a number of various remote-sensing sophisticated sensors. 

The moon Europa appears to be covered by a many-kilometre-thick layer of ice showing cracking ice plates on the surface. Past fly-bys detected characteristics of a deep saltwater ocean below the ice layer, exceeding the amount of water in the oceans here on Earth. A future landing probe would attempt to detect biosignatures of life (as we know it - I can't quite imagine what it would take to recognize a version we DON'T know).

Engineers and technicians unwrap and inspect the main body of NASA's Europa Clipper spacecraft after it was built and delivered by the Johns Hopkins Applied Physics Laboratory(APL) in Laurel, Maryland, to the agency's Jet Propulsion Laboratory in Southern California in early June. Credits: NASA/JPL Caltech/Johns Hopkins APL/Ed Whitman.

 

Jupiter's moon Europa.  Image Credit: NASA/somagnews.com

At 3,120 km diameter, Europa is the smallest of the four Galilean moons (a bit smaller than our Moon). It orbits Jupiter at a distance of about 671,000 km and is in a resonance relationship with the moons Io and Ganymede. It takes two orbits for Io to go around Jupiter to one orbit for Europa, four Io orbits for one Ganymede orbit. Jupiter itself has the major gravitational effect. These various interactions create complex gravitational flexing of Europa, which is likely to create heat in Europe's interior (to some degree, other Jupiter moons are similarly affected, of course). Perhaps these effects contribute to the cracked appearance of Europa's surface; maybe black smokers exist on Europa also, along with the extremophiles which are the bacterial basis for the existence of the black smoker anaerobic species in our oceans.  

Along with other moons, Europa is also subject to intense radiation which surrounds Jupiter. That situation is not beneficial for life (again, as we know it) on the surface of Europa, but might generate possibilities in the water under the ice shell (maybe turn it into beer?).

 

Close-up of a rugged area on Europa's surface

Source: NASA/JPL Published January 8, 2019:

During its twelfth orbit around Jupiter, on Dec. 16, 1997, NASA's Galileo spacecraft made its closest pass of Jupiter's icy moon Europa, soaring 124 miles (200 kilometers) kilometers above the icy surface. This image was taken near the closest approach point, at a range of 335 miles (560 kilometers) and is the highest resolution picture of Europa obtained by Galileo. The image was taken at a highly oblique angle, providing a vantage point similar to that of someone looking out an airplane window. The features at the bottom of the image are much closer to the viewer than those at the top of the image. Many bright ridges are seen in the picture, with dark material in the low-lying valleys. In the center of the image, the regular ridges and valleys give way to a darker region of jumbled hills, which may be one of the many dark pits observed on the surface of Europa. Smaller dark, circular features seen here are probably impact craters.North is to the right of the picture, and the sun illuminates the surface from that direction. This image, centred at approximately 13 degrees south latitude and 235 degrees west longitude, is approximately 1 mile (1.6 kilometres) wide. The resolution is 19 feet (6 meters) per picture element. This image was taken on Dec. 16, 1997 by the solid state imaging system camera on NASA's Galileo spacecraft. 

NASA has a link to detailed planned activities during a number of Europa Clipper fly-bys. Here it is: https://europa.nasa.gov/mission/about/

If you own a pair of reasonably sized binoculars (7x50, say) you can easily see the four starlike Galilean moons, and follow their orbits around Jupiter over hours and days. Telescopes will afford you a closer view, depending on the telescope's size. Exact positions, times, and names are listed in the RASC "Observer's Handbook" which contains a multitude of planetary, orbital, scientific data. It is used by both professional and amateur astronomers. If you are a member of the RASC, the handbook is one of the membership bonuses. 

Looking at the Galilean moons, I'm always amazed to think that Galileo's discovery of these moons had a direct effect on, and is perhaps the actual cause of the direction our scientific and cultural evolution has taken since then... life as we know it now.

Moonrise

 

Many people have little interest in astronomy. Most of them have never given thought, or don't know, for instance, the cause of the Moon's various phases, and its different locations in the sky from day to day.  The picture below was taken through our living room window, the Moon phase shown a day or so after full. The Moon and Earth,  as are all the planets and their moons in our solar system, are illuminated by the Sun. 

The Moon about a day after full.

I expected to see the Moon rise behind the the mountains at about that position and at that time, both from past experience (we've lived in our house for over 50 years), and rough calculations of thumb.

The Moon's speed in its orbit around Earth is such that it moves the distance of its own diameter (about 3500 km) eastward in an hour. That is its real motion in the sky, as is obvious when compared with the position of background stars. The Moon's apparently much larger motion westward is the result of Earth's daily rotation. 

The full Moon is always located in the sky opposite the sun's position in the sky on an imaginary straight  line from the Sun, to the Earth, and then the Moon. For the northern hemisphere in summer, the Sun rises in the northeast, and sets in the northwest. The full Moon on the same day rises in the southeast and sets in the southwest. The winter sunrise and sunset are again opposite each other: Sun southeast rise, southwest set, the full Moon northeast rise, northwest set.

Throughout the year, as the Earth orbits through the four seasons, the rising and setting points for Sun and Moon  change every day; none-the-less, the full Moon is always opposite the Sun. That implies that the position of the Sun in the sky 6 months later will be approximately where the full Moon is today, and the full Moon 6 months later will be approximately where the Sun is today. Opposing positions can also be applied to other phases of the Moon. For instance, first quarter Moon and last quarter are in the same relationship as full Moon and Sun. One difference is that their respective illuminations are opposite. In the northern hemisphere on Earth the first quarter shows the illuminated right side and the third quarter is its illuminated left side, as seen standing up, facing south. In general, all phases of the Moon before full are illuminated on the right side, all phases past full Moon are illuminated on the left side. The opposite is true for the mid-southern hemisphere, where you are looking north to find the Moon. Close to the equator, the Moon moves through the sky overhead, your left/right phase perceptions depend on the direction you're facing. 

An aside: in the northern hemisphere, due to the Earth's daily rotation, Sun, and at night the Moon and astronomical objects move in the sky from left to right, if you are facing south. If you're looking at the North Star, the stars move around it counterclockwise. The North Star is below the horizon for the Southern Hemisphere, there is no South Star. The stars move around the "South Point" clockwise and, facing north, all astronomical objects move from right to left. In the northern hemisphere, you can simulate all these effects by stretching out on the ground. If your head points south, the stars overhead appear to move like they do in the southern hemisphere (right to left); lie down in the southern hemisphere with your head pointing north, they move as they do in the northern hemisphere (left to right). The Cardinal Points North, East, South, and West are never changed. They are the same in both hemispheres. It all boils down to "personal positioning".

The Earth is not flat after all!

The Moon's average apparent diameter, as it appears from Earth, is about half of a degree. Also, the Moon in reality moves eastward about one half of a degree per hour (see above). In a day, that is a distance of about 12 degrees. In a month, Earth, along with the Moon, has moved along the Earth orbit by about 30 degrees. The orbit of the full Moon, say, from today's position with respect to background stars to the next time in the same relative position with the same stars is 27.3 days. That is the sidereal month. At that point the Moon is not full again, because of the 30 degree change in the Earth's orbital position. The Moon has to move about 2.2 days more before full phase occurs. Therefore, the synodic month, from full Moon to full Moon, or any other phase to the same phase again is about 29.5 days.

 The numbers shown here are all general approximations and ignore several other aspects of Earth and Moon orbits. For one thing, the plane of the Moon's orbit differs by 5 degrees from the Earth's orbital plane. The Earth's rotational axis is inclined by 23.5 degrees from the vertical to the Earth's orbital plane. Both Moon and Earth orbits are not circles; that also affects orbital speed and position. The imaginary line I mentioned connecting Sun, Earth, and full Moon is only really straight when the Moon is at the crossover points of Earth's and Moon's orbital planes. When lunar eclipse occurs the Earth is exactly between the Sun and the full Moon. With the new, invisible Moon is exactly between the Sun and Earth, solar eclipses occur. At other times, that line is "slightly bent".

As I mentioned in the beginning, past experience and simple calculations give me an approximate idea about the area in the sky where I should find the Moon, the planets or the major constellations and stars. There are much easier ways to do all this, of course. Nowadays, many computer-based highly accurate sky map applications for smart phones, laptops, and desktops are available. I use those quite often, too. What these apps don't do for me is give me a mental perspective of the spacial distribution of the Moon, Earth, Planets, and stars, and the immense time spans and distances in the universe, something like being on a trip in space, or looking at the sky through binoculars and telescopes.  

 You can get an accurate version of the numbers above in the RASC's Observer's Handbook. You can either purchase the book, or have it sent to you without cost if you are a member of RASC Vancouver or other RASC centres.