If you have access to a telescope or binoculars and you have a clear sky, you may be able to view Comet 45P/Honda-Mrkos-Pajdušáková near the Moon.
See link below.
Comet 45P/Honda-Mrkos-Pajdušáková
31 December 2016
06 September 2016
Proxima Centauri B
It has been recently announced that astronomers have discovered a possible terrestrial planet in the habitable zone around the star nearest to the Sun, Proxima Centauri. We discussed a little about Proxima Centarui when we discussed the nearest star system to the Sun, Alpha Centauri.
So what exactly does this mean? Terrestrial planets are those planets much like Earth in terms of size and composition. The habitable zone are the parts of a planetary system where water can be in liquid form on the surface of the planet. Remember, that water is a important to life in the universe.
Now, having a Earth-like planet in the habitable zone does not necessarily mean that the planet has water. We won't know for a long time, either.
So what exactly does this mean? Terrestrial planets are those planets much like Earth in terms of size and composition. The habitable zone are the parts of a planetary system where water can be in liquid form on the surface of the planet. Remember, that water is a important to life in the universe.
Now, having a Earth-like planet in the habitable zone does not necessarily mean that the planet has water. We won't know for a long time, either.
10 July 2016
July
July is the 7th month in both the Julian and Gregorian calendar. It has 31 days, and is one of the hotter months of the year in the northern hemisphere. We are going to discuss a little about the naming of the month.
In the Roman calendar, there used to be only 10 months, and July was the fifth month. It was original named Quintilis, which is Latin for fifth. When the Roman calendar changed to a 12-month calendar, it retained the name Quintilis. We will see more of this later on when we talk about the final four months of the year.
In 45 BCE, when the Julian calendar was introduced, then Roman dictator Julius Caesar had the calendar created to follow more along the lines of the actual orbit of the Sun. When he was assassinated the following year, they renamed Quintilis Julius after Caesar, and it was anglicized to July.
In the Roman calendar, there used to be only 10 months, and July was the fifth month. It was original named Quintilis, which is Latin for fifth. When the Roman calendar changed to a 12-month calendar, it retained the name Quintilis. We will see more of this later on when we talk about the final four months of the year.
In 45 BCE, when the Julian calendar was introduced, then Roman dictator Julius Caesar had the calendar created to follow more along the lines of the actual orbit of the Sun. When he was assassinated the following year, they renamed Quintilis Julius after Caesar, and it was anglicized to July.
30 June 2016
Leap Second
Everyone knows the leap day. Every four years (except century years not divisible by 100), an extra day is added to the year in February to keep the calendar in synch with the seasons.
However, there is also a leap second. This is used every couple of years to keep the Coordinated Universal Time close to the mean solar time. The reason why it is needed is that the Earth's rotation is slowing down, but not by a lot.
The second is added just before midnight on either June 30th or December 31st. The time would go from 23:59:59 to 23:59:60 to 00:00:00. The last time a leap second was added to the UTC was last June 30th.
However, there is also a leap second. This is used every couple of years to keep the Coordinated Universal Time close to the mean solar time. The reason why it is needed is that the Earth's rotation is slowing down, but not by a lot.
The second is added just before midnight on either June 30th or December 31st. The time would go from 23:59:59 to 23:59:60 to 00:00:00. The last time a leap second was added to the UTC was last June 30th.
28 June 2016
Negative Energy
Energy is what is called a scalar in physics. A scalar is a measurement that has a magnitude, but not a direction. Distance and time are other examples of a scalar. Vectors are measurements that have both magnitude and direction. Acceleration, force, and velocity are all examples of vectors.
Note: velocity and speed are not interchangeable in physics. Speed is a scalar, velocity is a vector.
Why is this important to know that energy is a scalar? Scalars are generally always zero or positive. So typically, the energy of a system is always zero or greater. The concept behind negative energy is this:
Suppose you have two objects separated by an infinite distance. The sum total of their energies is zero. Gravitational force then accelerates the two objects together. Therefore, the energy the system is increasing. But a closed system cannot change its energy. Therefore, the difference between the initial condition and the final condition is negative, hence negative energy.
Negative energy is a strange concept to understand and it's only theoretical since the above situation is very simplistic. However, if it does exist and we can harness it, negative energy can lead to humanity colonizing the galaxy (well, at least the local neighborhood). Negative energy can impact warp drives and may be used to stabilize wormholes.
Note: velocity and speed are not interchangeable in physics. Speed is a scalar, velocity is a vector.
Why is this important to know that energy is a scalar? Scalars are generally always zero or positive. So typically, the energy of a system is always zero or greater. The concept behind negative energy is this:
Suppose you have two objects separated by an infinite distance. The sum total of their energies is zero. Gravitational force then accelerates the two objects together. Therefore, the energy the system is increasing. But a closed system cannot change its energy. Therefore, the difference between the initial condition and the final condition is negative, hence negative energy.
Negative energy is a strange concept to understand and it's only theoretical since the above situation is very simplistic. However, if it does exist and we can harness it, negative energy can lead to humanity colonizing the galaxy (well, at least the local neighborhood). Negative energy can impact warp drives and may be used to stabilize wormholes.
27 June 2016
June
June is the sixth month in the Julian and Gregorian calendars. It is believed to be named after Juno, the wife of Jupiter or from the Latin iuniores meaning younger ones.
June is important astronomically as it contains the summer solstice for the Northern Hemisphere and the winter solstice for the Southern Hemisphere.
Important June events:
John Couch Adams, co-discoverer of Neptune, was born on June 5, 1819.
Johannes Muller, inventor of astronomical tables, was born on June 6, 1436.
Pope Gregory XIII was born on June 7, 1502.
Giovanni Cassini was born on June 8, 1625.
Johann G Galle, co-discoverer of Neptune, was born on June 9, 1812.
June is important astronomically as it contains the summer solstice for the Northern Hemisphere and the winter solstice for the Southern Hemisphere.
Important June events:
John Couch Adams, co-discoverer of Neptune, was born on June 5, 1819.
Johannes Muller, inventor of astronomical tables, was born on June 6, 1436.
Pope Gregory XIII was born on June 7, 1502.
Giovanni Cassini was born on June 8, 1625.
Johann G Galle, co-discoverer of Neptune, was born on June 9, 1812.
20 June 2016
Summer Solstice
June 20th, 2016 marks the official beginning of summer in the northern hemisphere. We call this day the summer solstice.
In astronomical terms, the summer solstice for the northern hemisphere occurs when the sun is the farthest north of the equator on the ecliptic. This angular distance is 23.5°, This angle also marks a line of latitude on the Earth called the Tropic of Cancer.
The Tropic of Cancer is so called because the summer solstice used to occur when the Sun was in the constellation Cancer and the latitude lines in the tropical zone. There is also a comparable line of latitude south of the equator called the Antarctic Circle. The latitude is 66.5° South and for anyone living south of this latitude (really, mostly penguins or anyone stationed in Antarctica), the Sun will never rise. Conversely, the Arctic Circle at 66.5° North, the Sun never sets. In fact, from the vernal equinox to the autumnal equinox, the North Pole is in perpetual sunlight, while the South Pole is in perpetual darkness.
The summer solstice marks the day of the year when the northern hemisphere receives the most light. From here on until the winter solstice, the days will only get shorter and the nights longer. In the southern hemisphere, the opposite occurs. Today marks the shortest day of the year and they are in winter time.
In astronomical terms, the summer solstice for the northern hemisphere occurs when the sun is the farthest north of the equator on the ecliptic. This angular distance is 23.5°, This angle also marks a line of latitude on the Earth called the Tropic of Cancer.
The Tropic of Cancer is so called because the summer solstice used to occur when the Sun was in the constellation Cancer and the latitude lines in the tropical zone. There is also a comparable line of latitude south of the equator called the Antarctic Circle. The latitude is 66.5° South and for anyone living south of this latitude (really, mostly penguins or anyone stationed in Antarctica), the Sun will never rise. Conversely, the Arctic Circle at 66.5° North, the Sun never sets. In fact, from the vernal equinox to the autumnal equinox, the North Pole is in perpetual sunlight, while the South Pole is in perpetual darkness.
The summer solstice marks the day of the year when the northern hemisphere receives the most light. From here on until the winter solstice, the days will only get shorter and the nights longer. In the southern hemisphere, the opposite occurs. Today marks the shortest day of the year and they are in winter time.
21 May 2016
Mars at Opposition
Mars will be at opposition on May 22nd, 2016.
From a previous post, we know that opposition occurs when the planet and the Sun are 180° away from each other in the sky. What this means is that when the Sun is setting, the planet will be rising. In the next couple of days, if you look to the east at sunset, Mars will be rising above the horizon. A great time to view Mars would be at midnight when it is near the apex of its path across the sky. Mars will be in Scorpius (the constellation opposite the Sun's location in Taurus) as seen here.
Because Mars is at opposition, it is the closest to us, but is still about 0.4 AU (60 million kilometers or 37.2 million miles) away from us.
From a previous post, we know that opposition occurs when the planet and the Sun are 180° away from each other in the sky. What this means is that when the Sun is setting, the planet will be rising. In the next couple of days, if you look to the east at sunset, Mars will be rising above the horizon. A great time to view Mars would be at midnight when it is near the apex of its path across the sky. Mars will be in Scorpius (the constellation opposite the Sun's location in Taurus) as seen here.
Because Mars is at opposition, it is the closest to us, but is still about 0.4 AU (60 million kilometers or 37.2 million miles) away from us.
03 May 2016
TRAPPIST-1 Planets
TRAPPIST-1 is an M8 dwarf star which is one of the coldest stars on the Hertzsprung-Russell Diagram. It has a surface temperature of about 2550 K (the Sun, by comparison has a surface temperature of 5800 K) and a mass of approximately 0.08 Solar masses.
Recently, astronomers led by Michael Gillon of the University of Liege announced that they discovered three planets orbiting TRAPPIST-1 using the transit method. The two closest are tidally locked to their parent star, much like the Moon is tidally locked to Earth. However, the third planet lies just at the outer edge or beyond the habitable zone of the star.
Theoretically, this planet could harbor life, but in all likelihood, it would nothing like Earth life. By being in the habitable zone, this means that water would be in liquid form, which astronomers believe would be necessary for life to exist.
Recently, astronomers led by Michael Gillon of the University of Liege announced that they discovered three planets orbiting TRAPPIST-1 using the transit method. The two closest are tidally locked to their parent star, much like the Moon is tidally locked to Earth. However, the third planet lies just at the outer edge or beyond the habitable zone of the star.
Theoretically, this planet could harbor life, but in all likelihood, it would nothing like Earth life. By being in the habitable zone, this means that water would be in liquid form, which astronomers believe would be necessary for life to exist.
02 May 2016
Transit of Mercury
On May 9, 2016, the planet Mercury will transit across the face of the Sun and for most of the Earth, the transit will be visible (or at least portions of it).
The transit begins at 11:12 UTC (Coordinated Universal Time measured at Greenwich, England) and ends at 18:42 UTC. To determine your time offset from UTC, Wikipedia has a good summary. For example, in Pittsburgh (where I live), we are currently only four hours behind UTC due to daylight savings time. So in Pittsburgh, the transit begins at 7:12 AM and ends at 2:42 PM.
To see the transit, you should not look directly at the Sun.. There are a couple of ways to look at it, however.
The transit begins at 11:12 UTC (Coordinated Universal Time measured at Greenwich, England) and ends at 18:42 UTC. To determine your time offset from UTC, Wikipedia has a good summary. For example, in Pittsburgh (where I live), we are currently only four hours behind UTC due to daylight savings time. So in Pittsburgh, the transit begins at 7:12 AM and ends at 2:42 PM.
To see the transit, you should not look directly at the Sun.. There are a couple of ways to look at it, however.
- Have a Sun filter for a telescope, binoculars, or camera.
- Watch it online at NASA.gov.
30 April 2016
Molecular Clouds
Molecular clouds are regions of gas and dust from which stars and planets form. They are generally colder regions, so are darker than the surrounding areas. They can only be seen when they are in front of a brighter region and appear as "holes" in space.
A good example of a molecular cloud is the Horsehead Nebula in Orion.
A good example of a molecular cloud is the Horsehead Nebula in Orion.
Credit and Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT
These clouds are also called dark nebula because they don't emit radiation in the visible spectrum. These are the regions of space where stars and planets form. The cloud will start to collapse because of an outside force, like the wavefront of a supernova. The collapse will also create rotation on the cloud. From the conservation of angular momentum, as the cloud collapses, the rotation also speeds up. At the core of the cloud, the density increases and the temperature increases. This is where the protostar is formed. The outer sections of the cloud are where planets, dwarf planets, asteroids, comets, and other bodies in a planetary system will form.
27 April 2016
The Satellite of Makemake
Makemake is a dwarf planet in the outer edges of the solar system in the Kuiper Belt. It was discovered in March 2005, and announced by Mike Brown in July of 2005. It is about 2/3 the size of Pluto, so it is relatively small. However, it was recently discovered that Makemake has a companion body discovered in April of 2016 (from images taken in April of 2015 from the Hubble Space Telescope). It is not the only dwarf planet with a satellite.
Pluto has five, including Charon. Eris, the largest dwarf planet by mass (Pluto is larger by volume), has one (Dysnomia). Haumea has two. Satellites around dwarf planets may be pretty common.
Pluto has five, including Charon. Eris, the largest dwarf planet by mass (Pluto is larger by volume), has one (Dysnomia). Haumea has two. Satellites around dwarf planets may be pretty common.
22 April 2016
April
April is the fourth month of both the Julian and Gregorian calendar. It was once the second month of the old Roman calendar until the Numa calendar was created in 700s BCE. Where does the name April come from?
There are many ideas. One is that is named for the Roman word aperire which means to open, as this it the first full month of spring and flowers begin to open. It could also be related the Greek goddess Aphrodite whose Roman equivalent Venus held the month sacred.
The zodiac constellations (according the pseudo-science astrology) are Aries (the ram) and Taurus (the bull). In actuality, the Sun is in the constellation Aries right now, but was in Pisces (the fish) up until April 19. The Sun won't be in Taurus until mid May. The original astrological signs were based on the Sun's position 2000 years ago and was covered on my post about the precession of the equinoxes. You can also revisit my post about the Zodiac, as well.
Next month, we'll talk about May...and a lot sooner than near the end of the month.
There are many ideas. One is that is named for the Roman word aperire which means to open, as this it the first full month of spring and flowers begin to open. It could also be related the Greek goddess Aphrodite whose Roman equivalent Venus held the month sacred.
The zodiac constellations (according the pseudo-science astrology) are Aries (the ram) and Taurus (the bull). In actuality, the Sun is in the constellation Aries right now, but was in Pisces (the fish) up until April 19. The Sun won't be in Taurus until mid May. The original astrological signs were based on the Sun's position 2000 years ago and was covered on my post about the precession of the equinoxes. You can also revisit my post about the Zodiac, as well.
Next month, we'll talk about May...and a lot sooner than near the end of the month.
17 March 2016
March
March is the third month of the Gregorian calendar. It is named after the Roman god Mars.
Did you know, in the old Roman calendar, it was actually the first month? The original Roman calendar contained ten months, from March through December. It wasn't until Julius Caesar introduced his namesake calendar in 46 BC.
Some interesting notes to know about March: it is the birth month of Albert Einstein (born March 14, 1879), it has the fun mathematical day called Pi (π) Day which is also 3-14, and it has the vernal equinox, which we will talk about later.
Did you know, in the old Roman calendar, it was actually the first month? The original Roman calendar contained ten months, from March through December. It wasn't until Julius Caesar introduced his namesake calendar in 46 BC.
Some interesting notes to know about March: it is the birth month of Albert Einstein (born March 14, 1879), it has the fun mathematical day called Pi (π) Day which is also 3-14, and it has the vernal equinox, which we will talk about later.
08 March 2016
Total Solar Eclipse for March 8-9, 2016
There will be a total solar eclipse today, but only if you are in the areas below. Australians and Southeast Asians will have the best view. Some in Hawai'i will see a partial solar eclipse.
See this link for more information.
02 March 2016
Leap Day
Under Julius Caesar, the idea of a leap day/leap year was added to help keep the seasons in alignment with the calendar. Leap days were added every four years to account for the orbit of the Earth around the Sun, which was approximately 365.25 days (it is actually 365.2425 days).
This calendar worked fine until 1582, when Pope Gregory XIII wanted to make sure that the Christian holy days fell around the same time every year. By 1582, the Julian calendar was out of sync with the seasons by 10 days. The calendar developed under Gregory was able to account for the difference between 365.25 days and 365.2425 days. We still have a leap day every four years, but to help account for above difference, this calendar did not have a leap year if the years was divisible by 100 but not by 400. For example, 2000 was a leap year since it is divisible by 400. But 1900 was not and 2100 will not be leap years. This will help keep the calendar in sync with the seasons until 9282, meaning an error of only 1 day every 7700 years. The Julian calendar had an error of 1 days every 128 years.
26 February 2016
Alpha Centauri
Alpha Centauri is the closest star system to our Sun. It is actually a triple star system, with Alpha Centauri A, a G2V star much like our Sun, Alpha Centauri B, a slightly smaller and cooler K1V star, and Proxima Centauri (also Alpha Centauri C), an M6V red dwarf. Proxima Centauri is named thus, because is the closest star to our Sun.
Alpha Centauri is approximately 4.34 light years away, and as shown above, the largest of the stars is very similar to the Sun. This stellar system is important and will be the first star system humanity will ever visit when we are finally able to leave our own Solar System. Right now, it would take about 81,000 years with our fastest spacecraft technology to reach the star system.
Once we get to Alpha Centauri, we will be able to see if it has planets similar to ours and if the planetary system would be recognizable to us. We would want to see if there were any Earth-like planets and if there could be life on them. Just like the Moon should be our first logical step in colonizing the Solar System, Alpha Centauri is the first logical step in exploring our galaxy.
Alpha Centauri is approximately 4.34 light years away, and as shown above, the largest of the stars is very similar to the Sun. This stellar system is important and will be the first star system humanity will ever visit when we are finally able to leave our own Solar System. Right now, it would take about 81,000 years with our fastest spacecraft technology to reach the star system.
Once we get to Alpha Centauri, we will be able to see if it has planets similar to ours and if the planetary system would be recognizable to us. We would want to see if there were any Earth-like planets and if there could be life on them. Just like the Moon should be our first logical step in colonizing the Solar System, Alpha Centauri is the first logical step in exploring our galaxy.
22 February 2016
Days of the Week
So we now finish up the days of the week, and the one thing I want you to take away from the past week is the Latin names for the days of the week. The moment calendar used today (the Gregorian Calendar) was a revision of the Julian Calendar which was based on the old Roman calendar. What this calendar gave us was the 7-day week. And the ancient Romans also thought that there were 7 celestial bodies orbiting around the Earth: the Moon, the Sun, Venus, Mercury, Mars, Jupiter and Saturn, which also happen to be what the Romans named the days of the week after.
21 February 2016
Sunday
Sunday. Depending on where you live, the first day or the last day of the week. Obviously, you can easily see that Sunday is named after the Sun. Let's look at Sunday in other languages.
French: dimanche
Spanish: domingo
Italian: domenica
German: Sonntag
Latin: dies Solis
German and Latin are also named after the Sun. What about the other romance languages? Those are actually derived from the Latin for Lord, dominicus. When Christianity became the prevalent religion, Sunday was referred to as the Lord's Day, hence the root for the Romance languages.
French: dimanche
Spanish: domingo
Italian: domenica
German: Sonntag
Latin: dies Solis
German and Latin are also named after the Sun. What about the other romance languages? Those are actually derived from the Latin for Lord, dominicus. When Christianity became the prevalent religion, Sunday was referred to as the Lord's Day, hence the root for the Romance languages.
20 February 2016
Saturday
It's Saturday! And you know that this means we'll look at Saturday in other languages.
French: samedi
Italian: Sabato
Spanish: Sabado
German: Samstag
Latin: dies Saturni
English and Latin have the same root, the Roman god Saturn, while the others refer to the day of Sabbath, which has always been Saturday. East Germans sometimes use Sonnabend, which literally means Sunday Eve.
French: samedi
Italian: Sabato
Spanish: Sabado
German: Samstag
Latin: dies Saturni
English and Latin have the same root, the Roman god Saturn, while the others refer to the day of Sabbath, which has always been Saturday. East Germans sometimes use Sonnabend, which literally means Sunday Eve.
19 February 2016
Friday
Friday, the best day of the week, if you ask me.
Let's see what Friday is in other languages.
French: Vendredi
Italian: Venerdi
Spanish: viernes
German: Freitag
Latin: dies Veneris
All the Romance translations are based on the Latin which translates to "day of Venus". What is the Germanic equivalent of Venus? Frigg (or Friya), the wife of Odin, who was also the goddess of love.
Let's see what Friday is in other languages.
French: Vendredi
Italian: Venerdi
Spanish: viernes
German: Freitag
Latin: dies Veneris
All the Romance translations are based on the Latin which translates to "day of Venus". What is the Germanic equivalent of Venus? Frigg (or Friya), the wife of Odin, who was also the goddess of love.
18 February 2016
Thursday
Thursday, the fourth day of the week or the fifth, depending on whether or not your week starts on Monday or on Sunday.
Let's look at Thursday in other languages:
French: jeudi
Italian: giovedi
Spanish: jueves
German: Donnerstag
Latin: dies Iovis
Looking at the Romance languages, they are all named after Jupiter, the supreme Roman god. He is also the god of thunder which leads to ... Thor in old Norse mythology. Yes, Thor was not the supreme Norse god, that was Oden, but because he was also the god of thunder, that's where we got Thursday. Donnerstag is also named after the Germanic Thor.
Let's look at Thursday in other languages:
French: jeudi
Italian: giovedi
Spanish: jueves
German: Donnerstag
Latin: dies Iovis
Looking at the Romance languages, they are all named after Jupiter, the supreme Roman god. He is also the god of thunder which leads to ... Thor in old Norse mythology. Yes, Thor was not the supreme Norse god, that was Oden, but because he was also the god of thunder, that's where we got Thursday. Donnerstag is also named after the Germanic Thor.
17 February 2016
Wednesday
Wednesday in other languages:
French: mercredi
Spanish: miercoles
Italian: mercoledi
German: Mittwoch (literally, midweek)
Latin: dies Mercurii
Romance languages are obviously named after Mercury.
English comes from Odin or Woden (Germanic god similar to Mercury).
German Mittwoch used to be Wodenstag.
16 February 2016
Tuesday
Tuesday in other languages:
French - mardi
Spanish - martes
Italian - martedi
German - Dienstag
Latin - dies Martis
As you can see, all the Romance languages are named after Mars, the Roman god of war and the fourth planet in the solar system. However, English and German are different. Who or what are they named after?
In English, Tuesday is named after the Norse god Tyr, who is the Norse god of combat. So in a way, Tuesday is named after the Roman god Mars, but with a Norse twist.
In German, there is some question that it may be named after Thingus, a Latinized version of a German god who may or may not be the same as Tiw or Tyr in Norse mythology.
French - mardi
Spanish - martes
Italian - martedi
German - Dienstag
Latin - dies Martis
As you can see, all the Romance languages are named after Mars, the Roman god of war and the fourth planet in the solar system. However, English and German are different. Who or what are they named after?
In English, Tuesday is named after the Norse god Tyr, who is the Norse god of combat. So in a way, Tuesday is named after the Roman god Mars, but with a Norse twist.
In German, there is some question that it may be named after Thingus, a Latinized version of a German god who may or may not be the same as Tiw or Tyr in Norse mythology.
15 February 2016
Monday
This post will be the first of a week long series of the history behind the names of the days of the week. Today, we will start with Monday.
Monday in some other languages:
French - lundi
Spanish - lunes
German - Montag
Latin - dies Lunae
Italian - Lunedi
What do these all have in common? Well, for one, French, Spanish, and Italian are all Romance languages (evolved from Latin), so all three look similar to the Latin word. German and English are also very similar because English is a Germanic language.
The thing that they all have in common is that they all roughly mean the same thing: day of the Moon. Monday is named after the Moon. And we will see as we go on, that most days of the week are named after celestial bodies (or something related to a celestial body).
Monday in some other languages:
French - lundi
Spanish - lunes
German - Montag
Latin - dies Lunae
Italian - Lunedi
What do these all have in common? Well, for one, French, Spanish, and Italian are all Romance languages (evolved from Latin), so all three look similar to the Latin word. German and English are also very similar because English is a Germanic language.
The thing that they all have in common is that they all roughly mean the same thing: day of the Moon. Monday is named after the Moon. And we will see as we go on, that most days of the week are named after celestial bodies (or something related to a celestial body).
11 February 2016
Gravitational Waves
Gravitational waves have been observed. for the first time. LIGO, the Laser Interferometer Gravitational-Wave Observer, detected gravitational waves created when two massive black holes merged over 1.3 billion years ago. Einstein predicted that they could exist, but up until now, we did not have the technology to detect them.
What exactly are Gravitational Waves? Think of them as ripples in space-time. When you drop a pebble in a still body of water, circular waves move out from where the pebble hits. A similar thing happens when an object with large masses on either end rotate. The masses create disruptions in space-time and as the masses rotate, those distortions propagate radially from the center of mass. When the two black holes were colliding, they were rotating about their common center of mass, and the black holes themselves created the ripples. However, the size of these ripples are extremely small. So how did LIGO detect these waves?
When a gravitation wave passes through a point in space, it can distort the point perpendicularly to the direction of travel. In one direction, space is stretched and in the perpendicular direction, space is squeezed. When the next wave passes, the stretching and squeezing are reversed.
What exactly are Gravitational Waves? Think of them as ripples in space-time. When you drop a pebble in a still body of water, circular waves move out from where the pebble hits. A similar thing happens when an object with large masses on either end rotate. The masses create disruptions in space-time and as the masses rotate, those distortions propagate radially from the center of mass. When the two black holes were colliding, they were rotating about their common center of mass, and the black holes themselves created the ripples. However, the size of these ripples are extremely small. So how did LIGO detect these waves?
When a gravitation wave passes through a point in space, it can distort the point perpendicularly to the direction of travel. In one direction, space is stretched and in the perpendicular direction, space is squeezed. When the next wave passes, the stretching and squeezing are reversed.
LIGO is an interferometer which is a system of telescopes that uses two or more telescopes to act effectively as a single telescope. What LIGO did to find gravitational waves was when one passed by, one arm of the interferometer was longer than the perpendicular arm. However, this difference is so small (1/10,000th the size of a proton), the precise measurements had to be made. That is why it took almost 100 years to detect gravitational waves.
09 February 2016
February
February is named for the Latin word februum which means purification. It is the shortest month, always lasting less than 30 days. It did not actually join the calendar until 713 BC, and was actually the last month (following January) until about 450 BC when January and February were moved to the beginning of the calendar.
The number of days in February varied between 23 and 27 days to account for the precession of the equinox and did not have the length of 28 days until the Julian calendar was established under the rule of Julius Caesar. Leap days were added every four years to account for the orbit of the Earth around the Sun, which was approximately 365.25 days (it is actually 365.2425 days and created problems in the 1580s which we will discuss later).
The number of days in February varied between 23 and 27 days to account for the precession of the equinox and did not have the length of 28 days until the Julian calendar was established under the rule of Julius Caesar. Leap days were added every four years to account for the orbit of the Earth around the Sun, which was approximately 365.25 days (it is actually 365.2425 days and created problems in the 1580s which we will discuss later).
08 February 2016
Any Requests?
Is there something you want to learn about that I haven't covered or didn't cover enough? Let me know in the comments section.
02 February 2016
Planet beyond Pluto?
Recently, there has been news that astronomers have found another planet beyond Pluto. At the moment, astronomers think the new planet is about 10 Earth masses and has a period of 20,000 years.
The orbit is highly elliptical with a perihelion somewhere between 200 to 300 AU and an aphelion between 600 and 1200 AU. We can also assume that since the planet is out beyond the orbit of Pluto, it has a density similar to that of Pluto, about 2000 kg/m³.
What do these assumptions mean? It could explain why it took so long for astronomers to find this planet, if it is really there. Using Kepler's laws, specifically, P²=a³, where P is the period of the orbit in Earth years and a is the semi-major axis in AU, we can determine the semi-major axis of the planet. With P at 20,000 years, we find that a is about 740 AU.
Using the density of Pluto and the mass of the new planet (10 Earth masses = 6x1025 kg), we can estimate that the radius of Planet 9 is about 41,500 km. For a perihelion of 200 AU, the angular diameter is only 0.01" (arcseconds) which is typical of a star. It is also possible that the planet has a low albedo, so it is very dim.
So, while it is possible that there is a planet beyond Pluto, it took this long to find it because it is so far away.
The orbit is highly elliptical with a perihelion somewhere between 200 to 300 AU and an aphelion between 600 and 1200 AU. We can also assume that since the planet is out beyond the orbit of Pluto, it has a density similar to that of Pluto, about 2000 kg/m³.
What do these assumptions mean? It could explain why it took so long for astronomers to find this planet, if it is really there. Using Kepler's laws, specifically, P²=a³, where P is the period of the orbit in Earth years and a is the semi-major axis in AU, we can determine the semi-major axis of the planet. With P at 20,000 years, we find that a is about 740 AU.
Using the density of Pluto and the mass of the new planet (10 Earth masses = 6x1025 kg), we can estimate that the radius of Planet 9 is about 41,500 km. For a perihelion of 200 AU, the angular diameter is only 0.01" (arcseconds) which is typical of a star. It is also possible that the planet has a low albedo, so it is very dim.
So, while it is possible that there is a planet beyond Pluto, it took this long to find it because it is so far away.
23 January 2016
Five Planets Visible
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.
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.
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.
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