- Email: [email protected]
Stars in the city
The back pages Puzzles The crossword, a puzzle about stamps and a quick quiz p52
Feedback Letters of note and rook-y errors: the week in weird p53
Twisteddoodles for New Scientist A cartoonist’s take on the world p53
Almost the last word Cycling no-handed and tidal effects: readers respond p54
The Q&A Gelong Thubten on Buddhism, science and mindfulness p56
Stargazing at home Week 3
Stars in the city
Abigail Beall is a science writer in Leeds, UK. This series is based on her book The Art of Urban Astronomy @abbybeall
What you need A phone with a stargazing app, but only if you get stuck
For next week Binoculars
Next in the series 1 Model the equinox 2 Find the North Star and Southern Cross 3 Test your area’s light pollution 4 Identify the craters of the moon See millions of years of history 5 Orion and Sirius: how to star-hop 6 Planet spotting: Mars, Mercury and Uranus 7 Taurus and the zodiacal constellations
LIGHT pollution makes stargazing in towns and cities more difficult, but that doesn’t mean you can’t see anything. By measuring the light, you will be able to work out what you can see in the best-available conditions and plan your stargazing trips accordingly. For this I’m going to use the constellation Pegasus, which is visible in the southern hemisphere between August and December and in the northern hemisphere from July to January. First, pick a clear night with little moonlight. Then minimise all light sources. If you live in a city, find an open green space and go right to the middle of it. Or, if you have access to a rooftop, go as high as possible. If all else fails, your garden or a high window will do, just turn off all the lights. Next you need to give your eyes time to adjust. If it is really dark, this could take 40 minutes. If you are surrounded by lights, you won’t need this long because your eyes will only adjust so much. Bear in mind that the process is ruined as soon as you look at a bright light and you will have to start again. A star’s brightness as seen from Earth is known as its magnitude. This is a logarithmic scale, which means stars with lower numbers are brighter. For example, Sirius is the brightest star in the night sky and has a magnitude of -1.46, while the North Star is 1.97. The sun is -27 and the International Space Station can reach -6. To find Pegasus in the north, use the Plough to find the North Star,
SERGEI MALGAVKO/TASS VIA GETTY IMAGES
You can measure light pollution in your area by counting stars, says Abigail Beall. You might be surprised by how many you see
Stargazing at home online
Projects will be posted online each week at newscientist.com/maker Email: [email protected]
as we did last week. Then draw an imaginary line from any star in the handle of the Plough, through the North Star, to get to Cassiopeia – a distinctive W or M-shaped constellation. Continue this line through the Caph star, which is at one end of Cassiopeia – the right if it looks like a W to you or the left if it is an M. This line will take you to four bright stars – all between 2 and 2.7 magnitude – that make the Great Square of Pegasus. In the southern hemisphere, the easiest way to find the Great Square at this time of year is to look due north at around 9pm. If you’re having difficulty, then a stargazing app will help.
Now count how many stars you can see inside the square. No stars means conditions aren’t great. One star means your visible magnitude is 4.5, five is 5.25. If you see seven, you are seeing stars of magnitude 5.5, and 13 stars takes you to 6. The best you can expect with the naked eye is 35 stars, which means you are seeing magnitudes of up to 6.5, but this only happens in the darkest skies with no moonlight. The results depend on your eyesight, too. But it doesn’t matter if someone else can see more than you, just that you know what you can expect to see. It won’t be a problem next week, though, since we will be looking at the moon. ❚ 5 October 2019 | New Scientist | 51
Feedback Letters of note and rook-y errors: the week in weird p53
Twisteddoodles for New Scientist A cartoonist’s take on the world p53
Almost the last word Cycling no-handed and tidal effects: readers respond p54
The Q&A Gelong Thubten on Buddhism, science and mindfulness p56
Stargazing at home Week 3
Stars in the city
Abigail Beall is a science writer in Leeds, UK. This series is based on her book The Art of Urban Astronomy @abbybeall
What you need A phone with a stargazing app, but only if you get stuck
For next week Binoculars
Next in the series 1 Model the equinox 2 Find the North Star and Southern Cross 3 Test your area’s light pollution 4 Identify the craters of the moon See millions of years of history 5 Orion and Sirius: how to star-hop 6 Planet spotting: Mars, Mercury and Uranus 7 Taurus and the zodiacal constellations
LIGHT pollution makes stargazing in towns and cities more difficult, but that doesn’t mean you can’t see anything. By measuring the light, you will be able to work out what you can see in the best-available conditions and plan your stargazing trips accordingly. For this I’m going to use the constellation Pegasus, which is visible in the southern hemisphere between August and December and in the northern hemisphere from July to January. First, pick a clear night with little moonlight. Then minimise all light sources. If you live in a city, find an open green space and go right to the middle of it. Or, if you have access to a rooftop, go as high as possible. If all else fails, your garden or a high window will do, just turn off all the lights. Next you need to give your eyes time to adjust. If it is really dark, this could take 40 minutes. If you are surrounded by lights, you won’t need this long because your eyes will only adjust so much. Bear in mind that the process is ruined as soon as you look at a bright light and you will have to start again. A star’s brightness as seen from Earth is known as its magnitude. This is a logarithmic scale, which means stars with lower numbers are brighter. For example, Sirius is the brightest star in the night sky and has a magnitude of -1.46, while the North Star is 1.97. The sun is -27 and the International Space Station can reach -6. To find Pegasus in the north, use the Plough to find the North Star,
SERGEI MALGAVKO/TASS VIA GETTY IMAGES
You can measure light pollution in your area by counting stars, says Abigail Beall. You might be surprised by how many you see
Stargazing at home online
Projects will be posted online each week at newscientist.com/maker Email: [email protected]
as we did last week. Then draw an imaginary line from any star in the handle of the Plough, through the North Star, to get to Cassiopeia – a distinctive W or M-shaped constellation. Continue this line through the Caph star, which is at one end of Cassiopeia – the right if it looks like a W to you or the left if it is an M. This line will take you to four bright stars – all between 2 and 2.7 magnitude – that make the Great Square of Pegasus. In the southern hemisphere, the easiest way to find the Great Square at this time of year is to look due north at around 9pm. If you’re having difficulty, then a stargazing app will help.
Now count how many stars you can see inside the square. No stars means conditions aren’t great. One star means your visible magnitude is 4.5, five is 5.25. If you see seven, you are seeing stars of magnitude 5.5, and 13 stars takes you to 6. The best you can expect with the naked eye is 35 stars, which means you are seeing magnitudes of up to 6.5, but this only happens in the darkest skies with no moonlight. The results depend on your eyesight, too. But it doesn’t matter if someone else can see more than you, just that you know what you can expect to see. It won’t be a problem next week, though, since we will be looking at the moon. ❚ 5 October 2019 | New Scientist | 51