For the first time in a decade, if you are an early riser, you will be able to see all five of the naked eye planets in the sky. For the next month, just before sunrise, Mercury, Venus, Mars, Jupiter, and Saturn will be visible in the sky to the east. This sort of alignment can only be seen just before sunrise or just after sunset because Venus and Mercury can never be far from the Sun in the sky. Check out this post from July 16, 2014.
Remember, planets do not twinkle as compared to stars. So you should be able to easily spot the planets in the sky compared to the stars. Just for note, Mercury will be the planet closest to the horizon and Jupiter will be the farthest. The order of the planets in the sky will be Mercury, Venus, Saturn, Mars, and Jupiter. If you have a powerful enough telescope, you also might be able to see Pluto near Mercury.
One other cool observation is beginning around the third quarter phase, the Moon will also be visible along with the five planets. As the Moon ages towards the New Moon, it will be among the planets in the sky.
Note: if you are really observant, you will be able to see a sixth planet. Comment below if you know which planet and why you will be able to see it.
23 January 2016
16 January 2016
Faster-Than-Light Travel
Since humanity first went into space, we've always wondered if there is a way for us to travel to the distant stars faster than the light from those stars reach us. Faster than light travel has been a mystery to us and something we want to figure out if we ever want to go beyond our own Solar System.
What is faster-than-light travel? Basically, it going faster than the speed of light which is 300,000 km/s or 671 million miles per hour. At that speed, we could reach Jupiter from Earth in a little under an hour. Neptune, at 2.795 billion miles from the Sun, could be reached in about 4 hours, the flight time from New York to Dallas. To reach the closest star, Proxima Centauri, would still take 4.22 years. Knowing this, is it possible we could achieve faster-light-travel?
Probably not because when we think of faster-than-light travel, we think of traveling through normal space using the known laws of physics. The one theory that will control whether or not we can travel faster than light is special relativity. This is Einstein's theory that describes the physics at travels at or near the speed of light. Hendrik Lorentz found that as the speed of an object increases, so does it mass. At low speeds, i.e. speeds we achieve on Earth, this increase in mass is negligible. However, at near light speeds, the mass increases so much that when an object travels at the speed of light, its mass becomes infinite. This is given by
What is faster-than-light travel? Basically, it going faster than the speed of light which is 300,000 km/s or 671 million miles per hour. At that speed, we could reach Jupiter from Earth in a little under an hour. Neptune, at 2.795 billion miles from the Sun, could be reached in about 4 hours, the flight time from New York to Dallas. To reach the closest star, Proxima Centauri, would still take 4.22 years. Knowing this, is it possible we could achieve faster-light-travel?
Probably not because when we think of faster-than-light travel, we think of traveling through normal space using the known laws of physics. The one theory that will control whether or not we can travel faster than light is special relativity. This is Einstein's theory that describes the physics at travels at or near the speed of light. Hendrik Lorentz found that as the speed of an object increases, so does it mass. At low speeds, i.e. speeds we achieve on Earth, this increase in mass is negligible. However, at near light speeds, the mass increases so much that when an object travels at the speed of light, its mass becomes infinite. This is given by
where γ is the Lorentz factor given by:
As you can see, as the velocity increase, the Lorentz factor decreases, until at v = c (the speed of light), γ = 0. And anything divided by 0 is infinite. So, sorry, we will never be able to travel through normal space at velocities greater than the speed of light.
So what about science fiction? They show spacecraft travelling faster than the speed of light, right? Well, technically, no. They have apparent faster than light velocity. What this means is that they follow laws of physics about which we do not know much. These laws that could, theoretically, allow apparent faster than light travel. I'm going to focus on two: warp drive in Star Trek and hyperdrive in Star Wars.
Warp drive describes exactly what it does: it warps space. A warp drive in a Star Trek ship creates a "warp bubble" around the ship allowing space in front of the ship to be compressed and the space behind it to be expanded. This allows the ship seemingly to travel faster than light.
This is called a Alcubierre drive, which is essentially a warp drive.
Star Wars, however, uses something a little more exotic. It uses something called hyperdrive, which is essentially creating a wormhole in space to allow the ship to travel across vast distances via a shortcut in hyperspace. Think of it as taking a piece of paper and folding it in half so that the two ends are about an inch apart. If an ant wanted to travel from a point on the top half of the sheet to a point on the bottom half of the sheet, it would have to travel the whole length of the sheet. Now, imagine that that ant could create a hole in the top half and a hole in the bottom half and is able to link those two holes together. The ant has created a wormhole allowing it to travel much faster between points than taking the conventional way.
via Space.com
These two methods of faster-than-light travel may someday be achieved. But the physics and engineering of how to accomplish them are not well understood, and for that which we understand, it requires a form of energy that we do not have the ability to create at this time. Both methods require negative energy which may be discussed at a future time.
09 January 2016
Ion Drives
Previously, I talked about ions. Remember, they are atoms that have either more or less electrons than protons. For ion drives, positive ions, also called cations, are used to propel the craft ahead.
The ions are created in a chamber where the electrons are stripped from an atom or molecule (many times xenon or ammonia, depending on the thruster type), then are accelerated via an electrostatic or an electromagnetic field.
Ion drives have a very high specific impulse, which means they are very efficient engines. Specific impulse is the ratio between the spacecraft's thrust (the force at which the spacecraft is being pushed along) and the weight of the fuel used to create that thrust).
However, the thrust from an ion engine is small since ions themselves are rather tiny. Ion engines are not great from getting place to place quickly in the solar system. Typically, ion drives will be used for space stations for maneuvering or for deep space probes. Though the thrust is tiny, over time, that thrust can add up to a large velocity for the spacecraft.
The ions are created in a chamber where the electrons are stripped from an atom or molecule (many times xenon or ammonia, depending on the thruster type), then are accelerated via an electrostatic or an electromagnetic field.
Ion drives have a very high specific impulse, which means they are very efficient engines. Specific impulse is the ratio between the spacecraft's thrust (the force at which the spacecraft is being pushed along) and the weight of the fuel used to create that thrust).
However, the thrust from an ion engine is small since ions themselves are rather tiny. Ion engines are not great from getting place to place quickly in the solar system. Typically, ion drives will be used for space stations for maneuvering or for deep space probes. Though the thrust is tiny, over time, that thrust can add up to a large velocity for the spacecraft.
Deep Space 1
Via NASA
Schematic of Deep Space 1
via NASA
08 January 2016
January
January. New Year (well, at least those of you following the Gregorian calendar). New Beginning. New blog post.
Sporadically, throughout the year, I am going to be discussing a little bit about the calendar because the calendar actually is based on astronomical phenomena. For example, the term for one-twelfth of a year is called month, which comes from the name Moon, derived for Proto-Germanic maenon. The division of the year into months comes from the lunar cycle, which is approximately 30 days.
I just want to begin this sporadic series by discussing where the name of January comes from. It is actually derived from the Roman god Ianus (no J's in Latin) who was the god of doorways and passages. He is also known as the two-headed god as he can see forward and also backwards, at the same time. Ianus is a god who can look in the past, yet still see peer ahead to the future. Good name for the month that begins a year.
Sporadically, throughout the year, I am going to be discussing a little bit about the calendar because the calendar actually is based on astronomical phenomena. For example, the term for one-twelfth of a year is called month, which comes from the name Moon, derived for Proto-Germanic maenon. The division of the year into months comes from the lunar cycle, which is approximately 30 days.
I just want to begin this sporadic series by discussing where the name of January comes from. It is actually derived from the Roman god Ianus (no J's in Latin) who was the god of doorways and passages. He is also known as the two-headed god as he can see forward and also backwards, at the same time. Ianus is a god who can look in the past, yet still see peer ahead to the future. Good name for the month that begins a year.
Subscribe to:
Posts (Atom)