Tonight's Sky for June 30: the Tunguska Event (1908)

It was on this date in 1908 that the biggest impact from a celestial body in recorded history took place over the remote Tunguska region of Siberia, Russia. 

June 30, 1908 dawned a normal morning in Siberia. Then, just past 7am, a blinding fireball as bright as the Sun came through the sky and exploded. Shock waves knocked people off their feet and windows were broken hundreds of miles away. For the next few days, nights as far away as London were as bright as day. Something extraordinary had happened, but the world would have to wait almost 20 years for scientists to pick up the case when Russian Leonid Kulik finally penetrated the vast wilderness in search of a meteorite crater and/or pieces of the space rock. He came up empty but found over 1,000 square miles of forest flattened, save a small area near the center of the region. Thanks to political instability and then WWII, the world would have to wait almost a generation for further investigation.

In the 1950s and 60s, a new generation of scientists entered the Tunguska forest in search for clues. Recalling damage patterns brought upon by nuclear weapons testing, the Russians theorized that the vast devastation was caused not by a meteor or comet impacting the Earth, but by one exploding above the Earth. Using models with match sticks on springs standing in for trees and small explosive charges for the impactor, the scientists determined that the impacting body, whatever it was, exploded about 5 miles above the Earth while coming in at an angle of around 30 degrees inclination from the horizon. The proof? Scientists were able to recreate the famous butterfly, complete with standing "trees" right above the detonation.

As for what caused the explosion in the first place, there is still lively debate in the scientific community on the asteroid vs. comet theories, with both sides having very valid arguments to support their ideas.

Perhaps the only thing that can be agreed upon is this: Tunguska serves as a stark reminder that the detection of near-Earth objects and the development of technologies to divert them from hitting the Earth should be a very pressing scientific undertaking.

Tonight's Sky for June 27: Third Quarter Moon

Today, the Moon, second brightest object in the sky, has reached the Third Quarter phase, which means that it is exactly 270 degrees around its orbit of Earth.

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon at a 90 degree angle relative to the Earth and Sun, we see the Moon as half lit and half dark, leading to the popular, erroneous phrase 'half Moon.'

After today, we will see less and less of the Moon as its lit side turns more away from us and heads toward a new lunar cycle.     

Tonight's Sky for June 26: The Latest Sunsets

Technical difficulties resolved, here we go again . . .
While the solstice (and shortest nights) was almost a week ago week, the latest sunsets occur now. Why is this? Short answer: celestial mechanics. As for why the Sun doesn't have its extreme rise/set dates on the day of the solstice, it all has to do with solar noon, the point in time wherein the Sun reaches its highest point in the sky, which is the basis for the timing of the solstice. Problem: the Sun doesn't always reach its highest point in the sky as seen from Earth at noon. In addition, at the time of the solstice, the lay is actually longer than 24 hours. Result: solar noon doesn't always sync up with measured noon, hence why extreme sunrises and sets do not occur on the Solstices.  

Tonight's Sky for June 21: Summer Solstice

Today is the longest day of the year for us living in the Northern Hemisphere. With the summer solstice comes the longest day of the year and the official start of the summer season.

So, why do we have seasons, anyway?

It's all about Earth's tilt. If the Earth were spinning on its axis with no tilt at all, everyone would be treated to days of identical length every day of the year, with latitudes nearer the equator having longer days than those nearer the poles. However, with the tilt, the angle of the Earth relative to the Sun changes as or planet moves about its orbit. On the Winter Solstice (shortest day of the year) the Northern Hemisphere is tilted up and away from the Sun. On the Summer Solstice (today), the Northern Hemisphere will be tilted down toward the Sun. On the equinoxes, the tilt is half way between the solstices. To see this effect, go out and observe the path the Sun takes through the sky for the course of day of winter).

Tonight's Sky for June 19: Full Moon

Tonight, the Moon will reach its full phase, which means that, as seen from Earth, it is directly opposite the Sun in the sky as seen from Earth and is at the half way point in its current orbit.

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, when the Moon is opposite the Sun and on the far side of Earth, we can see all of its lit side, which is why it appears to be “full.” In the coming nights, we will start to see less of the Moon as its lit side starts to turn away from us as seen from Earth and heads toward Third Quarter. 

Tonight's Sky for June 18: First American Woman in Space (1983)

On this date in 1983, Sally Ride became the first woman to enter space, which she did on the STS-7 mission flown by the space shuttle Challenger.

Sally Ride was born in 1951 in California and grew up with a fascination in science, which she credited her parents for encouraging. It was in 1977 as she was completing her doctorate that Ride saw an ad in the Stanford University student newspaper stating that NASA was, for the first time, going to start considering non-military applicants for its astronaut training program. Up until that time, all astronauts had been military test pilots, and male.
With this new opening to civilians, NASA was flooded with over 8,000 applications, from which it selected a mete 35 astronaut candidates, with Ride being among the lucky few. Ride's training program commenced in 1978, with certification being completed a year later.

However, Ride would have to wait 4 years to fly, when she was assigned as a mission specialist aboard the STS-7 mission on the shuttle Challenger. It was on June 23, 1983, that Ride broke the gender barrier by becoming the first American woman in space. At the time, according to Ride, the feat was not not on her mind but, only with the passage of time, did her accomplishment really begin to sink in. Ride would fly into space once more a year later before retiring from NASA in 1987.

After NASA, Ride used her immense science credentials to make a career for herself in academic as both a consultant, researcher, and professor. What could be considered the crowning achievement of Ride's non-astronaut career came in 2001 when she founded Sally Ride Science, a company that promotes science education through creation of classroom materials and programs as well as professional development for science teachers, all while continuing to serve as a consultant for various organizations.

Ride died of cancer on July 23, 2012.

Tonight's Sky for June 16: First Woman in Space (1963)

On this date in 1963, Valentina V. Tereskova became the first woman to enter space, which she did on the Vostok 6 mission.

Valnentina Tereshkova was born on March 6, 1937 in the village of Maslennikovo. In her early life, Tereshkova was a textile worker before she became interested in skydiving. Following Yuri Gagarin's flight in April, 1961, it was decided that, having launched the first man into space, the Soviets should have a new goal:” launch the first woman into space. Beating out hundreds of other applicants and the other 4 finalists, Tereshkova launched into space aboard Vostok 6 on June 16, 1963. In all, Tereshkova would spend 3 days in space, orbiting the Earth 48 times, logging more orbital time than all the American astronauts up to that point combined.

However, there was an irony to Tereshkova's flight: the first female astronaut corps would never fly another member and would be itself disbanded in 1969. It would not be until 1982 when another woman would enter space.

Tonight's Sky for June 15: Be Alert for Aurora

Earth is entering a high-speed  stream of solar wind today, which is already creating G1 class geomagnetic storms. Experts at NOAA are advising high latitude skywatchers to be alert for aurora, commonly known as the Northern Lights, to keep an eye on the sky tonight. 

Tonight's Sky for June 14: The Earliest Sunrises

While the solstice (and shortest nights) will not occur for about another week, the earliest sunrises occur now. Why is this? Short answer: celestial mechanics. As for why the Sun doesn't have its extreme rise/set dates on the day of the solstice, it all has to do with solar noon, the point in time wherein the Sun reaches its highest point in the sky, which is the basis for the timing of the solstice. Problem: the Sun doesn't always reach its highest point in the sky as seen from Earth at noon. In contrast, the Sun is at its peak elevation about a week before the solstice in summer, which means that, solar noon being about 8 minutes before Earth noon, that also means that the sunrise occurs about 8 minutes earlier, too.  

Tonight's Sky for June 9: Johnann G. Gallee is Born (1812)

On this date in 1812, Johann G Gallee, the man who discovered Neptune, was born in Radis, Germany. At an early age, Gallee excelled in academics and eventually became a teacher before becoming assistant at the Berlin Observatory in 1835. Gallee's supervisor there was none other than Johann Franz Encke of comet fame. Using a 9-inch refractor, Gallee proceeded to discover 3 comets and an inner, dark ring surrounding Saturn.

In 1846, using calculations from French astronomer Urbain le Varrier, Gallee discovered the planet Neptune, whose locations was theorized from orbital oddities discovered in the path Uranus took around the Sun, which suggested an eighth, more distant planet.

Following his discovery of Neptune, Gallee would work as both a professor and observatory director. In all, Gallee published over 200 scientific works in a long career. Gallee died in 1910 at the age of 98.

Tonight's Sky for June 8: Christian Huygens Dies (1695)

On this date in 1695, Christian Huygens, the man who discovered Saturn's largest moon, Titan, died at the age of 66. A leading scientist of his time, Huygens made scientific contributions in the areas of what. In terms of astronomy, Huygens invented a 50 power refracting telescope, which he then used to discover the first moon of Saturn, Titan, and complete the most detailed examination of Saturn's rings up to that time, becoming the first man to suggest that Saturn was, in fact, surrounded by a ring at all. In addition, Huygens is noted for his making of the first drawing of the Orion Nebula and for his discovery of several nebulae and binary stars.

Tonight's Sky for June 6: Venus at Superior Conjunction

Today, the planet Venus has reached superior conjunction. What does that mean? In layman's terms, Venus will be directly opposite the Sun as seen from Earth in a Venus, Sun, Earth alignment. End result: the planet will be at its worst point for viewing. This stands in contrast to an inferior conjunction, during which Venus would come directly between the Sun and Earth. 

Tonight's Sky for June 5: Mercury at its Best

Want to join a small club of people who have seen the planet Mercury? Well, here's your chance as the first planet from the Sun will be making its best appearance of the fall this morning.

Of all the Classical Planets (those known to the Ancient Greeks and Romans), Mercury is by far the hardest to spot because, as seen from Earth, it never gets very far away from the Sun. As a result, Mercury is often obscured from view by the Sun's glare.

As of today, Mercury has reached a point in its orbit called greatest elongation, which is a fancy way of saying that, as seen from Earth, Mercury is as far from the Sun as it will get on this orbit and making its best morning appearance of the year. How good is it? So good that Mercury sets about an hour and a half after the Sun! So good that, even 30 minutes after sunset, Mercury is still about 10 degrees up from the horizon. To simulate, hold your fist vertically at arm's length. While that may not seem overly high, for elusive Mercury, that's quite good.

So, take a moment or two, go out just before dawn, and try to spot Mercury. If you are successful in spotting the speedy planet, you are accomplishing something that the great astronomer Nicolaus Copernicus (who rediscovered the idea of a sun-centered solar system) supposedly never did.

Tonight's Sky for June 4: New Moon

Today, the Moon, second brightest object in the sky, has reached the New Moon phase, which means that it is directly between the Sun and Earth, and thus invisible for us Earthlings as of now. 

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon directly between the Earth and Sun, e can't see any of its lit side.

After today, we will see more of the Moon each night as its lit side turns more toward from us and heads toward first quarter.

Tonight's Sky for June 3: Old Moon Meets Mercury

How thin of a Moon have you seen? How about one that's just barely a day before New and only 2% illuminated? Well, if you have never seen a Moon this thin, tonight's your chance to do so as such a Moon will be making an appearance in this morning's sky just before sunrise. 

To see the Moon, you'll need a good Eastern horizon. How good? One with less than 3 degrees of obstruction. To simulate this, hold two fingers vertically at arm's length to simulate 3 degrees. Hint: if you can't think of a good location off-hand, scout out one during the day. Location found, arrive there about 15 minutes before sunrise and start looking, preferably with optical aid. The bad news: you'll have to hurry because, as soon as the Sun clears the horizon, you can forget about seeing the Moon. To aid matters, Mercury is in the area, too.

Tonight's Sky for June 2: Saturn at Opposition

Tonight, the planet Saturn, 6^th from the Sun, will be at opposition. What does that mean? In short, if viewed from above, the Sun, Earth, and Saturn would be in a straight line in that order, with Saturn exactly opposite the Sun in the sky as seen from Earth. End result: Saturn rises as the Sun sets and Saturn sets as the Sun rises, meaning that Saturn is up all night. Oh yes, opposition technically takes place tomorrow but tomorrow brings a very worthy sight that deserves its own article.

Tonight's Sky for June 1: Short Nights

Today brings the month of June, and with it, the shortest nights of the year as the Solstice arrives on the 20th, signaling the shortest night of the year. However, while June nights may be short, they're long on sights by reading the below article, so try and get out for a look. 

The June Sky

The arrival of June also heralds the first day of summer and thus, the Summer Solstice, the longest day of the year. Since the length of day/night varies with latitude (the more North you go, the more extreme the lighting), not all people will be having equal length nights on the longest day of the year. On the other hand, one thing is common for all Northern Hemisphere observers: the nights are sort, especially when considering that it the approximately 1 ½ hours after sunset and before sunrise aren't truly dark. Now the good news: the summer sky is a cosmic picture book.

Cool Constellations

By the time June arrives, some of the Spring constellations are already taking their annual dives out of view. Among these are Hydra, Cancer, and, to a lesser extent, Leo. By the arrival of June, the Big Dipper signpost is starting to become obsolete. As the Dipper begins its annual dive, on the other end of the arc,Corvus and Crater are already disappearing but Bootes and Virgo are coming into their best placements of the year. By the time July comes, you'll only be able to speed on to Spica under a truly dark sky. Besides the already mentioned herdsman and virgin, and crown, Hercules, the Summer Triangle (made up of constellations Lyra, Cygnus, and Aquila), Ophiuchus, and Serpens are all flying high at this time of year, too. For those who like to stay up later, Libra and Scorpius are also on the rise, as is deep sky treasure trove Sagittarius along with the ghostly arch across the sky that is the Milky Way. By the time the sky starts to brighten around 4:30am (sunrise is before 5:55 in mid month), a fall preview in the form of Pegasus, Andromeda, Aries, Capricorn, Aquarius, and even Pisces Australis is on tap, too.

Planetary Perceptions

On the planetary front, June marks a transition in that, for the first time in months, the majority of the planets are well-placed by the time the sky becomes dark which, this time of year, is rather late, but at least seeing the majority of planets won't involve staying up well past the arrival of true night. By the time it gets dark, Jupiter is in the Southwest and Mars, closely followed by Saturn, which comes to opposition on the 3^rd, are in the Southeast. The good news is that three of the best planets to view with a telescope are near opposition this month, the bad news is that, thanks to the flattening ecliptic plane, their placement is less than ideal because viewing them requires looking through a lot of atmosphere which, in a telescope, can result in unsteady seeing at high power. Hint: dusk often offers a window of steady air good for planet viewing. Additionally, Mars's racing away from Saturn will slow until,come month's end, it becomes stationary as its retrograding period ends. Moving into the morning, Mercury will make a good for this time of year appearance mid-month. Venus? It's lost in the Sun's glare all of June but will be reappearing, albeit barely, come next month.