stars

August Sky Spotlight

Astronomy and Physics, Earth, News

2nd: Moon at Perigee

On August 2nd, the Moon will be at its closest spot to Earth. This is called perigee.

7th: 1st Quarter

The Moon will be in its first quarter phase!

9th: Moon and Jupiter; Mercury in Greatest Western Elongation

The Moon and Jupiter will meet in the constellation Scorpio in the Southwestern sky.

Saturn, Venus, and Mercury in a dawning sky. Source: universetoday.com

Since Mercury is in between the Earth and the Sun, Mercury is always in the daytime sky. As Mercury goes around the Sun, it gets closer and farther away from the Sun in the sky. On the 9th, Mercury will be as far from the Sun as it gets. This is called greatest western elongation. This is when Mercury is at its best viewing because it’s not washed out by the Sun.

11th: Venus and Sun

On the 11th, Venus and the Sun will be together in the constellation Cancer! However, the Sun’s brightness will make this nearly impossible to view. Look towards (but not at) the rising Sun in the East.

12th: Moon, Saturn, and Pluto; Perseid’s Peak

The Moon, Saturn, and Pluto will be together in Sagittarius on the 12th. To see them, look towards the Southern sky.

In addition to seeing the Moon and planets, this night will feature one of the best shows the sky puts on: a meteor shower. The Perseid Meteor Shower will peak the night of the 12th and into the morning of the 13th. Look to the Northeast to see the show. Unfortunately, the bright Moon will inhibit viewing, but there will still be plenty to see!

15th: Full Moon, Venus at its Brightest 

The 15th will bring a full moon! And, if you look at the dawn sky, you will see a very bright Venus.

17th: Moon and Neptune; Moon at Apogee

The Moon and Neptune will appear together on the Eastern side of Aquarius. In addition, the Moon will be at apogee, it’s farthest point from Earth.

21st: Uranus and Moon

On the 21st, Uranus and the Moon will be seen in the Eastern sky in Aries.

23rd: Last Quarter; Venus and Mars

The Moon will be in its last quarter phase on the 23rd, while Venus and Mars will be together in the sky. They will be near the Sun in the constellation Leo.

29th: Mercury, Moon, and Sun

On the 29th, Mercury, the Moon, and the Sun will all be together. Look to the dawn sky to see them.

30th: Moon, Venus, and Mars; New Moon; Moon at Perigee 

The Moon, Venus, and Mars will be near the Sun; dawn will bring the best viewing. However, the new moon may be difficult to spot. Finally, the Moon will have returned to its closest point to the Earth.

31st: Sun and Mars

The Sun and Mars will be together in the constellation Leo.

Dyson Spheres: Smart or Stupid?

Astronomy and Physics, Earth, News

The other day my dad made a bold claim: Dyson spheres are stupid. I told him that they were not stupid, and he replied that they are because they’re physically impossible. 

I have to admit, he may have a point there. I mean, a true Dyson sphere would have to be quite large. That would take a lot of materials. Does the Earth have enough materials? Does the solar system? 

A Dyson sphere is a theoretical structure that encompasses a star. This structure would harvest as much sunlight as possible.

Olaf Stapledon made the first mention of Dyson spheres in his book Star Maker, but Freedman Dyson later proposed them in a scientific journal as a solution to an advanced civilization’s energy shortage. We rank hypothetical advanced civilizations on the Kardashev Scale, which is based on energy consumption. Currently, humans are not advanced enough to show up on the scale. However, a civilization with a Dyson sphere would be a Type II civilization—they would be able to harness the energy of their star. 

The sun is constantly producing 386 septillion watts of energy. Less than a billionth of a percent of this energy reaches the Earth. Humans harvest even less than this. Clearly, there is a ton of missed solar energy. 

But how would a Dyson sphere actually work? If it were to encompass the sun, but not the Earth, we would no longer receive sunlight. That wouldn’t work; it’s common knowledge that we need sunlight for life. So maybe it should follow the Earth’s orbit, with a little gap for the Earth. Or maybe it should be a little bigger than the Earth’s orbit and hold us inside too. Either way, that would be an astronomically large structure. The Earth is 93 million miles from the sun, so a sphere of that size would have a surface area of 109 quadrillion miles squared. My dad is right, that would be (nearly) impossible. There are not enough materials on the Earth. Luckily, there are enough materials in the solar system to build one. However, I wouldn’t count on it. 

An artist’s concept of a Dyson sphere. Source: CapnHack, via energyphysics.wikispaces.com

Okay, so we can’t have a Dyson sphere. But maybe we can have a Dyson part of a sphere? Or a Dyson fleet of satellites? Some (my dad), may argue that this is not a true Dyson sphere, but we could harvest far more energy than we do now. Right now, humans can only dream of a Dyson sphere. We don’t have the technology to build such a thing. Even a simpler version would be way out of our league. An array of satellites would need carefully calculated orbits. However, some of these orbits would probably overlap, thus blocking the very light they were sent to collect. 

While a Dyson sphere would be really cool, we don’t need to go to space to harvest light for energy. I mean, we have plenty of working solar panels on Earth. Plus, they’re becoming more popular; solar energy has been increasing for years and continues to do so. While solar energy isn’t as efficient at producing energy as fossil fuels are, you don’t have to pay for sunlight. 

Maybe Dyson spheres are in our future—not our near future, of course. I, for one, don’t have a lot of hope. I think they’re a cool theoretical structure, but I believe they will remain exactly that: theoretical. I would also like to say that my dad is not right. Dyson spheres are not dumb. We just have to be smart enough to build them.

July Sky Spotlight

Astronomy and Physics, Earth, News

2nd – New Moon, Total Solar Eclipse

July will start off as strong as June did! On only the second day of the month, we will have a total solar eclipse. Most of South America will be able to see at least a partial eclipse. Check Time and Date to see if you’re in the path!

3rd – Moon with Mars and Mercury

Astronomers call the sliver after a new moon a young moon. July’s young moon will be hanging out with Mars and Mercury in the constellation Cancer.

4th – Earth at Aphelion

The Earth’s orbit around the Sun is not a perfect circle, it’s an ellipse. This means that at some point, it must be at it’s furthest point from the Sun. That is in July! Aphelion is when a planet is farthest from it’s sun. This won’t affect our life at all, it’s just a neat fact.

9th – First Quarter, Saturn at Opposition

On July 9th, the Moon will be in it’s first quarter phase. This means that the left half will be dark and the right half will be light.

In addition, Saturn will be at opposition. This means that Earth will be directly between Saturn and the Sun.

13th – Moon with Jupiter

Jupiter and the Moon will be together in the constellation Scorpius in the Southern sky.

15th – Moon with Saturn

Saturn will be just East of the nearly full moon. They will be together in the constellation Sagittarius in the Southern Sky.

16th – Full Moon, Partial Lunar Eclipse

Most of the world (not including North America) will be able to see the Partial Lunar Eclipse! Check Time and Date to see if you’re in the path. If, like me, you are not in the path, enjoy the bright, beautiful full moon.

20th – Moon with Neptune

The Moon will be with Neptune in the constellation Aquarius in the Eastern night sky.

24th – Last Quarter, Moon and Uranus

On the 24th, the Moon will be in it’s last quarter with Uranus. They will be in Aries.

28th – Southern Delta Aquariid Meteor Shower Peaks

From midnight to dawn, and especially at 2 a.m., we will be able to see meteors originating from Aquarius. The moon will be a dark crescent, so the meteors will be easier to see. It is more visible from the Southern hemisphere than from the Northern Hemisphere.

31st – New Moon

Finally, on the last day of the month, we will end the same way we began: with a new moon.

Happy July viewing!

Another Galaxy Coming to Space Near You!

Astronomy and Physics, Beyond, News

Space continues to dazzle the eye! NASA recently posted this photo of Messier 90. Messier 90, also called NGC 4569, is a spiral galaxy located in the constellation Virgo about 90 million light years away from the Earth.

This image is a composite of light from the infrared, visible, and ultraviolet parts of the spectrum. The black portion of the photo is just a consequence of the camera used.

Source: ESA/Hubble & NASA, W. Sargent et al.

The most fascinating thing about Messier 90 is that the galaxy is moving towards us.

Most galaxies are moving away from us, with a few notable exceptions, including the Andromeda Galaxy. The galaxies move away because the universe is expanding. On a larger scale, everything moves away from us. However, on a more local scale, this expansion isn’t as intense, so galaxies are able to move towards one another.

Astronomers know Messier 90 is moving towards us because it is blue-shifted. The stars that make up galaxies produce photons, the particles of light, in every wavelength of the electromagnetic spectrum. When photons interact with atoms, such as the hydrogen and helium in stars, certain wavelengths are “blacked out” from the spectrum in what are called absorption lines. Absorption lines always occur at the same wavelength for each specific element. Therefore, scientists know exactly where the lines should be. Furthermore, they know exactly which elements a star contains based on these lines alone.

As a source moves towards the observer, the light waves are compressed, making them appear shorter. This causes the absorption lines to move to the shorter wavelength part of the spectrum, or towards the blue part of the visible spectrum. This is why we call them blue-shifted.

The same thing happens when galaxies move away, but instead, the wavelengths get longer. We call this red-shifted. In fact, the large number of red-shifted galaxies is how Edwin Hubble discovered the universe is expanding!

Messier 90 is a member of the Virgo Cluster, a neighbor of our own Local Group. The Virgo Cluster is another small cluster in our supercluster. The Virgo Cluster is thought to be whipping member galaxies around, causing some to be heading towards us. Astronomers think this because Messier 90 is not the only blue-shifted galaxy in the Virgo Cluster. Messier 86 is also blue-shifted!

Messier 90’s center has lots of active star formation, but this does not extend to the edges of the galaxy. Astronomers believe that this is another consequence of the galaxy’s membership in the Virgo Cluster. They theorize that other galaxies in the cluster have stripped Messier 90 of its interstellar material, quenching star formation. In addition, scientists believe that supernovae in the center of the galaxy blew star-forming material out of the galaxy.