NYC Comets
The Moon, Venus, Jupiter, and the M1 bus
From the Universe Down to Earth Dept.: I took this (rather primitive) snapshot a day after the dramatic triple conjunction of the Moon, Venus, and Jupiter. The Moon has moved well to the upper left, though Venus and Jupiter remain next to each other. I took the picture right in front of a bus stop, and didn’t realize until later that I had caught the “magic” M1 bus. The M1 bus goes up Park Avenue to Harlem, but M1 is also astro-speak for the Crab Nebula. I thought I'd use this bus to demonstrate how vast astronomical distances really are.
The Crab, an expanding cloud of gas and dust that surrounds the remains of a supernova whose explosion was visible in Earth’s skies in 1,054 AD, was the first entry in pioneering comet hunter Charles Messier’s catalogue of “comet imposters,” objects that today we know as star clusters, nebulae, and galaxies (thus the designation M1, or Messier 1). I got to wondering, how long would it take for the M1 bus, traveling through space at its normal city-bus speed, to reach the celestial M1—the Crab Nebula (don’t ask me how—it’s a magic bus), as well as the other space objects visible in this picture. (The Crab itself is far too faint to be seen here, and is hard to see from the city even in a telescope due to its low surface brightness.)
The Moon’s mean distance from Earth is 384,000 km, or just short of 240,000 miles, so that at an average speed of 10 mph (16 kph), which is probably on the fast side for a city bus, factoring in traffic and stops, the M1 bus would pass the Moon, or at least cross its orbit, in about 24,000 hours, which is 1,000 days or 2.73 years. Venus, when closest to Earth, is 38.2 million km, or 23.7 million miles—it would take the bus close to 2.4 million hours, or 100,000 days to get there, about 274 years. Jupiter, at closest, is 588 million km, or 365 million miles from us. It would take some 4,170 years for our intrepid bus to pass Jupiter’s orbit.
Now, on to the Crab Nebula, and here we see the dramatic increase in distances when you leave our solar system for interstellar space. A light-year is a unit of distance, not of time—it represents the distance light travels in a year, about 5.9 trillion miles (9.5 trillion km). The Crab is some 6,300 light-years, or some 37 quadrillion miles away from Earth. For our magic bus to reach the celestial M1, the site of this ancient stellar explosion, going at its normal city-bus speed, it would take some 422 billion years, roughly 100 times the current age of the Earth, and about 100 times as long as the Sun is expected to survive. As a friend quipped, if you’re going to take the M1 bus to the Crab Nebula, you’d better pack a lot of sandwiches!
The Moon, Venus, Jupiter, and the M1 bus
From the Universe Down to Earth Dept.: I took this (rather primitive) snapshot a day after the dramatic triple conjunction of the Moon, Venus, and Jupiter. The Moon has moved well to the upper left, though Venus and Jupiter remain next to each other. I took the picture right in front of a bus stop, and didn’t realize until later that I had caught the “magic” M1 bus. The M1 bus goes up Park Avenue to Harlem, but M1 is also astro-speak for the Crab Nebula. I thought I'd use this bus to demonstrate how vast astronomical distances really are.
The Crab, an expanding cloud of gas and dust that surrounds the remains of a supernova whose explosion was visible in Earth’s skies in 1,054 AD, was the first entry in pioneering comet hunter Charles Messier’s catalogue of “comet imposters,” objects that today we know as star clusters, nebulae, and galaxies (thus the designation M1, or Messier 1). I got to wondering, how long would it take for the M1 bus, traveling through space at its normal city-bus speed, to reach the celestial M1—the Crab Nebula (don’t ask me how—it’s a magic bus), as well as the other space objects visible in this picture. (The Crab itself is far too faint to be seen here, and is hard to see from the city even in a telescope due to its low surface brightness.)
The Moon’s mean distance from Earth is 384,000 km, or just short of 240,000 miles, so that at an average speed of 10 mph (16 kph), which is probably on the fast side for a city bus, factoring in traffic and stops, the M1 bus would pass the Moon, or at least cross its orbit, in about 24,000 hours, which is 1,000 days or 2.73 years. Venus, when closest to Earth, is 38.2 million km, or 23.7 million miles—it would take the bus close to 2.4 million hours, or 100,000 days to get there, about 274 years. Jupiter, at closest, is 588 million km, or 365 million miles from us. It would take some 4,170 years for our intrepid bus to pass Jupiter’s orbit.
Now, on to the Crab Nebula, and here we see the dramatic increase in distances when you leave our solar system for interstellar space. A light-year is a unit of distance, not of time—it represents the distance light travels in a year, about 5.9 trillion miles (9.5 trillion km). The Crab is some 6,300 light-years, or some 37 quadrillion miles away from Earth. For our magic bus to reach the celestial M1, the site of this ancient stellar explosion, going at its normal city-bus speed, it would take some 422 billion years, roughly 100 times the current age of the Earth, and about 100 times as long as the Sun is expected to survive. As a friend quipped, if you’re going to take the M1 bus to the Crab Nebula, you’d better pack a lot of sandwiches!