The night of October 5-6, 1923, forever changed the way astronomers saw and studied the cosmos. It was believed the Milky Way we see on clear moonless nights was the ‘universe’. Little did they know a simple 45-minute photograph would throw them a curve. It was long suspected a small patch of light located in the constellation of Andromeda was a cloud and referred to as the Andromeda Nebula.
The American astronomer Edwin Hubble set his sights on imaging this object with the massive 100-inch Hooker telescope at the Mount Wilson Observatory in California, the largest telescope in the world at that time. Placing a 4 by 5-inch photographic glass plate at the back of the grand telescope, he exposed the camera on the ‘cloud’. Because of the immense light-gathering power of the large telescope, the image revealed individual stars including a variable star called a Cepheid. These types of stars help astronomers determine distance. With this valuable measuring tool, the object was determined not to be part of our so-called ‘universe’ but a completely different one. It is officially called the Andromeda Galaxy residing some 2.5 million light-years away and containing an estimated one trillion stars. Since then many more galaxies have been imaged and their distance measured.
By 1929, Hubble showed that the universe was expanding faster than the speed of light which is hard to imagine. But all galaxies seem to be moving away from each other except for the merging galaxies whose gravity attracts each other such as our local group. This is how galaxies grow. So if galaxies are racing away from each other, they must have all started from a single point long long ago. In 1931 the Belgium priest’s father George Lemaitre, considered the Father of The Big Bang, stated “The day of the Big Bang, was a day without a yesterday”.
By the 1940s radio waves were first detected both from the sun and a supernova, the remains of a massive star that exploded in our galaxy that is named the Crab Nebula. The 200-inch Palomar Telescope in California was the largest in the world in 1949. The larger the telescope mirror, the farther astronomers can peer into space and the farther we see back in time.
The ’60s and ’70s saw Apollo astronauts landing on the moon six times, two Viking crafts parked on the planet Mars as well as launching identical Voyager 1 and 2 crafts measuring about the size of a subcompact car. They were designed to take closeup images as well as collect data from the outer planets and their moons. These were Jupiter, Saturn, Uranus, and Neptune. Launched 46 years ago, they are now 24 billion and 20 billion kilometres respectively from Earth.
Other than using ground-based telescopes with giant mirrors piercing the cosmos in optical light, technology has now allowed astronomers to study the cosmos in radio, microwave, infrared, ultraviolet, X-rays and gamma-rays. However, we are not restricted to earth-bound instruments. Spacecraft such as the Hubble Space Telescope, Chandra X-ray, Spitzer, Compton Gamma-ray and the newly launched James Webb Space Telescope as well as many more are hard at work viewing the cosmos in amazing detail.
The sole purpose of the orbiting Kepler Space Telescope was to search for exoplanets, and planets orbiting other stars in our galaxy. To date, there are more than 5,500 confirmed planets and thousands of candidates yet to be confirmed. But the majority of these worlds would be as large as Jupiter but closer to their star as Mercury is to the sun. The first ground-based discovery of an exoplanet was back in 1995. It is believed there are possibly more planets than stars in the Milky Way. There are a very small number of planets thought to be located in the ‘Goldilocks Zone’ such as Earth where oceans stay liquid. Too close to the star water would boil away, and farther out would freeze. We have recently received samples from the asteroid Bennu, delivering pristine material from the origins of the solar system after the birth of our sun, dating back about five billion years.
I am looking forward to seeing boots on the moon in 2025 as well as the first humans on the planet Mars in about 10 to 15 years. Decades ago a rendez-vous with the sun was an unthinkable goal for obvious reasons. The Parker Solar Probe is presently studying our daytime star close-up and personal. At times it dives very close in the solar atmosphere before retreating in elliptical orbits. On September 17 of this year, it approached a mere 7.26 million kilometres above its surface at a speed of 635,266 kilometres per hour or a staggering 176 kilometres per second. For reference, the Sun lies 150 million kilometres away. The heat shield is designed to keep the internal electronics a nice 30 degrees Celsius while the outer part is exposed to 1,400 degrees Celcius
I believe we will eventually discover a new type of physics that could explain the workings of dark matter and dark energy that is thought to have played a role in the creation of the universe. We have the technology as well as the ambition to pursue and unlock the mysteries of our fascinating cosmos. The path to discovery is ever-evolving and I cannot wait for the next big discovery.
Known as “The Backyard Astronomer”, Gary Boyle is an astronomy educator, guest speaker, monthly columnist for the Royal Astronomical Society of Canada as well as a STEM educator. He has been interviewed on more than 55 Canadian radio stations as well as various television stations across Canada and the U.S. In recognition of his public outreach in astronomy, the International Astronomical Union has honoured him with the naming of Asteroid (22406) Garyboyle. Follow him on Facebook and his website: www.wondersofastronomy.com