Status Updates From Simply Astronomy (DK Simply)

Looking up at the centre means gazing into the very centre of the Milky Way, which is also the location of the supermassive black hole Sagittarius A

The human eye looks for patterns. The first constellations were grouping of stars that ancient people used for navigation, timekeeping, or storytelling.

8 out of 10 US children born today will not be able to see the Milky Way

The cosmological principle suggests that all parts of the universe were once connected. It supports the theory that the universe originated in the Big Bang and then expanded. The largest scale structures we see today originate from energy fluctuations in the early universe that have been spread out, leaving filament of matter surrounding empty voids.

The stars in a globular cluster of gravitationally bound to each other. They follow complex orbits within spherical distribution that is more tightly packed towards the centre.

Compared with open clusters, globular clusters contain more stars – up to several million – and the stars are older: typically 10 billion years, almost as old as the universe itself. Laura clusters are some of the first parts of a galaxy to form, perhaps before the disc. New staff formation has largely ceased, all the raw materials in the initial gas cloud having been used up.

Stars that are born together stay together, at least initially, in groups called clusters. There are two main kinds of cluster: open and globular. And open cluster is a loose group of stars formed from the same cloud of gas and and dust.

Super massive black holes, more than 100,000 times the mass of the sun, I thought to lie at the centres of most large galaxies, and they may play a role in galaxy formation

Supernova can admit more light than several billion sons and outshining entire galaxies

Stars can end spectacularly bright explosions called supernovae… briefly out shining and entire galaxy, a supernova usually fades within a few months

Cool the stars glow red, emitting mostly low energy, long wavelength light; the hottest stars are blue, admitting mostly high energy, short wavelength light.

Stars would collapse under their own weight without the energy generated in their core. The pressure from expanding hot gas and radiation balances the inward pull of gravity.

The moon’s gravitational pool is the main cause of earths ocean tides

Some parts of earth surface experience stronger gravity than others. This is because earth is not perfectly round but rather slightly squashed, so that it is wider at the equator.

Most of the mass and energy in the universe is in the form of a mysterious invisible substance or force known as dark energy that is causing the expansion of the universe to accelerate. A possible explanation is that space is not simply. “Nothing” but instead has intrinsic properties that oppose gravity and stop the universe from contracting.

…Dark matter could be ordinary matter that does not much radiation. But it seems more likely to be made up of sub subatomic particles that do not interact with radiation at all. {there is so much we cannot see, and therefore do not know if we base our experience of the world on what we can observe as humans}

We see objects such as stars and planets because they emit or reflect light or other radiation. But the ordinary matter in these objects account accounts for just 5% of all matter. About 25% is matter in an invisible form called dark matter. We know it is there only because its gravity affects ordinary matter….

The first gravitational ways were detected exactly 100 years after they were predicted by Albert Einstein

When an object with mass accelerates (undergoes a change in its velocity), it sends out ripples that travel through space time at the speed of light. These ripples are called gravitational waves.

According to Einstein’s general theory of relativity, Gravity is the effect that these distortions have on the path that an object takes through space-time

In the early 20th century, Albert Einstein and others realise that space in time are not separate entities but, in fact, closely linked. The three dimensions of space and the single dimension of time can be combined into four dimensional realm called space time. This idea has important implications for how objects move through time and space because mass and energy distort space time…

… the distance light has travelled from an object to reach us is called the look back distance. But the current actual distance to the same object is greater and it’s called the proper distance.

Light travels incredibly fast, but it still takes time for light from an object in space to reach earth. So when we look at a celestial object, we see it as it was in the past. The further we look into space, the further we see into the past. When talking about the distance to these remote objects, we have to remember that space is continually expanding….

Galaxies and other objects are not getting larger, nor are they moving through space. Instead, space itself is expanding, carrying objects with it.

Despite its name, the Big Bang was not an explosion into space but a rapid expansion of everything, including space itself.

At first, the universe consisted only of energy. But within the first minuscule fractions of a second, he had expanded rapidly and a sea of matter enforced particles had emerged. The universe continues to expand to this day. {don’t we all}

All forms of electromagnetic radiation travel through space at the speed of light

Visible light is the most familiar form of EM radiation. Other forms include infrared, radio waves, and x-rays. He’s different in their wavelength and the way they interact with matter. The full range of wavelength is called the electromagnetic spectrum.

Electromagnetic radiation is energy that travels in the form of waves. Along with matter, it is one of the main components of the universe. All forms of ordinary matter EEM radiation, which can travel through empty space as well as some types of matter.