Nova in Delphinus transforms into a celestial chameleon

I plotted my observations of Nova Delphini 2013 through Aug. 22 on a simple graph to create a curve showing how the nova’s brightness has changed with time. The bottom axis shows the date; the vertical axis the nova’s magnitude. After a leap from 17th magnitude (far left) to around 4 1/2, the star has been slowly fading.

Time to check in on this month’s bright nova in Delphinus. After plateauing at magnitude 5.0 last weekend, Nova Del 2013 has been slowly fading ever since. By last night it had slid to 5.8 or just a tad brighter than the naked eye limit. The simple plot or light curve I compiled using my own binocular observations clearly shows its steady decline. Whether the star will continue to fade or bounce back is anyone’s guess. Novae can surprise just like comets do. They can also change color as we’ll see in a moment.

Chart to help you find the nova and estimate its brightness down to around magnitude 7.1. Click for larger version.

Now that the moon is rising later, skywatchers with dark, rural skies should be able to spot the nova with the naked eye again very soon. If you’ve been keeping a log of its brightness, click HERE for instructions on how to build your own light curve. I’ve included an updated chart for you to use to estimate the star’s brightness in the coming nights.

Through the telescope the nova has been a colorful sight. Early on it twinkled pale yellow but now has deepened in hue to yellow-orange. It’s still in the fireball phase with the white dwarf star hidden by fiery hydrogen gas and an expanding cloud of debris.

Closeup of prominences along the limb of the sun seen during a 1999 total solar eclipse. The flames glow in red H-alpha light. Nebulas also give off the familiar red of H-alpha as stars buried within them excite hydrogen gas to glow. Credit: Luc Viatour

As novae evolve they’ll often turn from white or yellow to red. Emission of what’s called hydrogen alpha light gives novae their warm, red color. Hydrogen, the most common element in stars, gets excited through intense radiation or collisions with atoms (heat).

Nova Delphini 2013 on Aug. 21. Credit: John Chumack

Once energized, hydrogen’s electrons “move upstairs”, ie. jump from a lower energy level to a higher one. Just as quickly, they can drop back down “downstairs”. When they do, each releases a smidge of light in the deep red end of the rainbow spectrum called hydrogen alpha or H-alpha. Nova-red comes from electrons dropping from the “third floor” to the “second floor” inside the hydrogen atom.

Novae take on a pink or red color for several reasons according to Arne Henden, director of the American Association of Variable Star Observers (AAVSO).

Nova illustration with an expanding cloud of debris surrounding central fireball emitting red hydrogen-alpha light.

“Energy from the explosion gets absorbed by the surrounding material in a nova and re-emitted as H-alpha,” said Henden. Not only that but as the explosion expands over time, the same amount of energy is spread over a larger area.

“The temperature drops,” said Henden, “causing the fireball to cool and turn redder on its own.” As the eruption expands and cools, materials blasted into the surrounding space condense into a shell of soot that absorbs that reddens the nova much the same way dusty air reddens the sun.

So why does it appear yellow-orange right now?

“That’s the underlying continuum (bluish light from the explosion) mixing with the H-alpha from the expanding fireball. Red and blue together make orange.”

Finally, I’m often asked how far away the nova is. According to the most recent study (reported 8/23), based on the rate of decline of the nova’s brightness, the star is some 13,000 light years from Earth. Very far! That means it must be incredibly brilliant.

A lot’s going on right now with Nova Delphini – an expanding fireball, formation of a debris cloud, cooling and reddening. And to think you can sample all this with little more than a pair of binoculars from your front yard. Amazing.

Light-gulping atmosphere and solar storms keep us on our toes

Monday evening’s sunset was all red and orange from heavy haze combined with the normal “thick air” the sun encounters when near the horizon. Rarely the sun can appear blue, when particles from volcanoes, forest fires and industrial pollutants are just the right size to scatter away the warmer hues of sunlight. Credit: Bob King

The persistent haze that’s made for lovely orange moons and ruddy sunsets has moved on, leaving a blue sky once again. I can’t say I miss the milky sky look, but I did enjoy those fireball sunsets.

Most of the air in our atmosphere is concentrated in the bottom 10 miles. Compared to our planet’s diameter, this airy shell is about as thin as the plastic wrap you use to cover an item in the microwave. The lower you go in the atmosphere, the thicker the air is and the greater the concentration of suspended dust particles, pollutants and water vapor.

The sunset sun takes the long path through the lower, thickest part of the atmosphere and gets heavily filtered. The noontime sun passes through a minimal amount of air. Illustration: Bob King

When the sun rides high in the sky, its light takes a very direct path to Earth, penetrating the extremely thin outer atmosphere, zipping through the lower 10 miles and arriving at the surface to light up the day. The air molecules on this short path only remove a sliver of the sun’s blue and violet light and scatter it to create a blue sky. To the eye the it appears pale yellow-white.

Light from the sunset or sunrise sun (left) and the noonday sun are a study in color contrasts. The sun’s white light is a combination of all the colors of the rainbow spectrum. Thicker air near the horizon removes most of the cool colors from the sun’s light, leaving red and orange. Credit: Bob King

Now take a look at the sunset sun (which also applies to sunrise). Its light comes in at such a low angle that it passes through hundreds of miles of dense and dusty air in the bottom 10 miles of atmosphere. All the colors are scattered or absorbed by the air except for the warm reds and oranges. These have the ability to penetrate where the others can’t. The same is true for the moon.

A recent August sunset photographed by astronauts on the space station. The nighttime Earth is in the foreground. The white band is the entire lower atmosphere;  above it are streaky octilucent clouds  about 50 miles (80 km) where the air is extremely rarified. Further up it’s airless outer space. Credit: NASA

Flying along at over 17,100 mph (27,600 km/hr), astronauts aboard the International Space Station astronauts experience some 16 sunsets and sunrises a day – one every 90 minutes. Their view of the atmosphere is more extensive than ours. They look low over the curvature of the Earth to see the deep red ball of the sun setting in what appears to be a very thin skin of air. Above it, the sky quickly transitions to blue and then black. Seen from 250 miles high, nearly all of Earth’s atmosphere lies far below the spacecraft.

An astronaut can see a sunset and stars (higher up) all at once, since her gaze quickly leaves the atmosphere for the vastness of airless space.

Here on the planet’s surface at the bottom of the atmosphere the transition from sunset to starry night takes time; the sun continues to make the air glow even when it’s well below the horizon. An hour an a half must pass before it’s night.

The prediction model for the coronal mass ejection leaving the sun on Aug. 21 that could affect Earth on the 24th. You’re watching for the crescent-shaped cloud headed outward toward the yellow dot (Earth) in the animation. Credit: Goddard Space Flight Center

While we’re on the topic of the sun, two coronal mass ejections earlier this week may increase our chances of seeing the aurora beginning late tonight through Saturday. The first involved an eruption of a large cloud of fiery hydrogen gas called a prominence or filament on Aug. 20. A second smaller filament came barrelling our way on the 21st. We’re not talking anything big, but skywatchers in southern Canada and in the northern border states should keep an eye out for northern lights.

Cassini releases 1,400 image mosaic of Earth waving at Saturn

A mosaic of more than 1,400 images of taken around the world of people waving back at NASA’s Cassini spacecraft the day it took a picture of Earth as part of a larger mosaic of the Saturn system. The images arrived at NASA via Twitter, Facebook, Flickr, Instagram, Google+ and e-mail. Click for large version. Credit: NASA/JPL-Caltech

Are you in this photo? People around the world shared more than 1,400 images
of themselves as part of NASA’s Wave at Saturn event on July 19. Cassini used its high-resolution camera that day to snap a portrait of the pale blue dot Earth alongside the planet Saturn. Meanwhile, back on the planet, we waved back.

A small cropped portion of the mosaic pictured above. Credit: NASA/JPL-Caltech

“While Earth is too small in the images Cassini obtained to distinguish any individual human beings, the mission has put together this collage so that we can celebrate all your waving hands, uplifted paws, smiling faces and artwork,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory.

Earth is the blue dot in this photo taken by the Cassini spacecraft at Saturn on July 19, 2013 from a distance of 898 million miles (1.44 billion km). The dark side of Saturn, its bright limb, the main rings, the F ring, and the G and E rings are clearly seen. Credit: NASA/JPL-Caltech/Space Science Institute

Tonight’s Full Moon could hit your eye like a big pizza pie

The nearly full moon is another “ball” in play during a soccer game last night in Duluth, Minn. Credit: Bob King

The full August moon, called the Sturgeon or Red Moon, will roll its cyclopean eye around the heavens tonight, beaming from the east around the time of sunset and lighting your path until dawn. Stare it back in the face while you’re out for an evening stroll.

I’ll never forget an evening long ago when my good friend Rick looked up at the moon and started singing “when the moon hits your eye like a big pizza pie, that’s amore” from the classic Dean Martin tune “That’s Amore”: Since he tends to be on the serious side, I had to chuckle when he burst out in song.

And who can deny that the broad white cratered plains look like so much mozzarella sprinkled around the dark, sausage-like forms of the lunar seas?

Large areas of the U.S. are experiencing typical hazy summer skies from dust, humidity and forest fires this August, making the moon look paler than usual especially at moonrise.


Sorry, couldn’t resist. Dean Martin and Jerry Lewis sing “That’s Amore”

If you’re one of the lucky ones to have a deep blue sky tonight, you’ll see the moon crest the horizon on schedule. Many of us will have to wait a few minutes for the moon to first clear the haze. I suspect it will look ghostly orange for a time until it rises high enough for its true brilliance to show. Click HERE and key in your location to find the time of moonrise.

Last night the hazy atmosphere served as an ideal filter for observing the nearly full moon through the telescope. Normally its glare is intense – you walk away from the scope blinded in one eye, practically stumbling. Not yesterday. The thick air made the moon easy on the eyes and tinted the lunar globe the color of September straw.

Why you should care about asteroid 101955 Bennu

Selection of radar images of asteroid 101955 Bennu, formerly known as 1999 RQ36, made with the Goldstone radio dish in Goldstone, Calif. in 2010. It doesn’t look like much but we’ll soon know it intimately. Credit: NASA

In September 2016 NASA will launch a very special mission. The target: near-Earth asteroid 101955 Bennu. The primary objective of the Origins, Spectral Interpretation, Resource Identification, and Security– Regolith Explorer (OSIRIS-REx) mission is to return the first pristine samples of carbon-rich material from the surface of a primitive asteroid.

“Primitive” in regard to asteroids means original material formed at the beginning of the solar system that’s been little altered by heat or pressure. Look around you and you won’t find these sorts of rocks on Earth. Most have been reworked and recycled through water and wind erosion and the great engine of plate tectonics.

While there are plenty of primitive asteroids out there, Bennu stands out as the most easily accessible one by space probe.

Contest winner Michael Puzio

Third grader Michael Puzio from North Carolina named it after an Egyptian mythological bird associated with the sun, creation and rebirth. A fitting name given Bennu’s origin at the time the clock first starting ticking in our planetary system.

Puzio was one of more than 8,000 students from around the world who entered the “Name That Asteroid” contest sponsored by the University of Arizona, the Planetary Society and LINEAR Project.

Illustration showing OSIRIS-REx in orbit around asteroid Bennu. Credit: NASA

With a girth of about 1,600 feet (0.5 km) Bennu’s a larger than average Earth-approaching asteroid. It orbits around the sun every 436 days (1.2 years) and passes close to the Earth every six years.

Why should you care about this hunk of rock? During those close approaches, Bennu comes within 278,867 miles (448,794 km) of our blue orb. Calculation of its future orbits indicate that Bennu has one of the highest impact probabilities in the next few centuries of any known asteroid.

The OSIRIS-REx spacecraft will extend a sampling device to gather a little over 2 ounces (60 g) of Bennu’s soil called regolith. Credit: NASA

Currently there’s a 1 in 1800 chance of impact with Earth on September 24, 2182. Another study by mathematician Andrea Milani reveals eight potential hit opportunities between 2169 and 2199. Little Bennu could turn into an angry bird.

Not only do scientists need to study the asteroid up close to gain a deeper understanding of the origin and evolution of asteroids and planets, but also to precisely determine its orbit and composition. In particular, we need to know how solar heating affects Bennu’s orbit. Something as simple as baking in the afternoon sun can have dramatic consequences over an asteroid’s lifetime.

Heat radiating from the hot “afternoon” side of an asteroid acts like a gentle rocket thrust that gradually changes an asteroid’s orbital speed. It’s called the Yarkovsky Effect. Because Bennu rotates from east to west instead of west to east like the Earth, the thrusting action causes its orbit to shrink inward toward the sun. Credit: NASA

Heat absorbed by Bennu during the day radiates back into space, pushing back against the asteroid like a rocket thruster. All those tiny pushes add up over the centuries, causing Bennu to slow down and its orbit to shrink. Whether a shrinking orbit will ultimately reduce or increase the probability of an impact, no one knows. That’s why getting up close will help nail down Bennu’s future amblings.

OSIRIS-REx is set to launch in September 2016 and reach the asteroid in October 2018. Once in orbit, the probe will map and study the surface from a distance of between 3 and 0.4 miles (5 and 0.7 km) for 505 days.

OSIRIS-REx will release the sample canister for re-entry back into Earth’s atmosphere and landing by parachute in Utah in September 2023. Credit: NASA/Goddard/University of Arizona

During this time the probe will extend the SAM or Sample Acquisition Mechanism down to the surface and collect at least 2.1 ounces (60 grams) of pristine material. The sample will be returned to Earth in a capsule that will float down by parachute over the Utah desert in September 2023.

Fragments of the Sutter’s Mill carbonaceous chondrite that fell in Sutter’s Mill, Calif. on April 22, 2012. Credit: NASA

Based on studies from Earth, Bennu most resembles the carbon and organic chemistry-rich carbonaceous chondrite meteorites. The Sutter’s Mill meteorite that fell in California last April is similar to what we expect for Bennu – dark, crumbly and rich in ancient clays and organics.

That chip-off-an-asteroid we could handle – it broke up harmlessly in the atmosphere. If Bennu came to Earth and remained intact, well, that would be another thing altogether.

Nova update, new radar pix of asteroid 2005 WK4, a phony double star

AAVSO chart for binocular users showing the nova and comparison star magnitudes. Click to download a full-size version. Copyright: AAVSO

Before we embark on today’s topic, let’s update where we’re at with Nova Delphini 2013. For the past day it’s plateaued around magnitude 5.0, maybe even rising a tad to 4.9. It remains easily visible in binoculars high in the southeastern sky at nightfall.

Light from the nearly full moon now drenches the sky, making it nearly impossible to glimpse the nova with the naked eye. Dark skies return about Aug. 23. Let’s hope it hangs in there till then.

On August 8 NASA scientists used the 230-foot (70-meter) Goldstone radar antenna in Goldstone, Calif. to bounce radio waves off near-Earth asteroid 2005 WK4.

Sequence of radar images of 2005 WK4 obtained on August 8 at Goldstone. The asteroid looks roughly oval-shaped with a bulge near the equator and some flat regions. Click for large image. Credit: NASA/JPL-Caltech/GSSR

By studying the reflected radar echoes, they reconstructed a sequence of images of the giant boulder, estimated at between 660 and 980 feet (200-300 m) in diameter. In a delightful coincidence that’s about as big as the 1,000-foot Arecibo radio telescope in Puerto Rico, the largest in the world. Astronomers used this dish to observe 2005 WK4 in July 2012.


Video of 2005 WK4 on Aug. 7 by Gianluca Masi. The asteroid appears only as a point of light in even the largest optical telescopes. The radar technique not only gives precise positions of nearby asteroids but also reveals their shapes and surface features

The asteroid missed Earth by a long shot - 1.93 million miles (3.1 million km) – but the data gained by radar studies will help refine 2005 WK4′s orbit well into the future. It also transformed what had been a mere point of light into a real world, albeit a small one. The Goldstone sequence covers 6 1/2 hours during which the asteroid completed 2.4 rotations.

The moon and stars Alpha and Beta Capricorni form a right triangle tonight in binoculars. The field of view shown above is about 5 degrees. Stellarium

While you’re out gandering at the nova tonight, give a look at the big, bright moon in your binoculars. About 4-5 degrees to its left on the opposite side of the field of view are two bright stars, Alpha and Beta Capricorni in Capricornus the Sea Goat. Alpha looks like the perfect double star, where you might envision each in orbit around the other. Guess again. It’s a total fake – just a chance alignment that convincingly mimics the real thing.

Below it shines Beta. Here we have a genuine double with a 6th magnitude companion orbiting close by to the west. The moon helps us find Alpha and Beta Cap with ease, but glare could make spotting Beta’s companion a bit of a challenge at least tonight. Give it a try to see for yourself.

Delphinus nova and Comet ISON update Aug. 17

Nova Delphini 2013 photographed through a 12-inch scope on Aug. 16. Credit: Efrain Morales Rivera

I caught Nova Delphini 2013 again in binoculars between clouds last night fading a bit to magnitude 5.0. That’s about where it’s at this morning the 17th according to the AAVSO (American Association of Variable Star Observers) website. That puts it a half mag. fainter than yesterday morning’s peak.

Novae can fade away quickly or jump up and down in brightness for some time, so if you’re thinking it might be on its way out this soon, have hope. Either way, this remarkable object bears close watching in binoculars.

If you’d like to contribute your observations of the nova’s brightness to science for use by professional astronomers when they research on the nova, I highly recommend joining the AAVSO. I’ve been a member since 1982 and it’s been a blast. Literally. My favorites stars are dwarf novae that pop off regularly and unannounced like the fireworks that still rattle my neighborhood long after the 4th of July. Click HERE to apply for membership.

A very faint Comet ISON photographed early this morning Aug. 17 at the start of twilight. Credit: Michael Jaeger

How about Comet ISON? Michael Jaeger, Austrian amateur astronomer and astrophotographer extraordinaire, took a photo of it just this morning (Aug. 17) when the comet was just 3 degrees above the horizon at the start of morning twilight. He estimated its brightness at magnitude 13, indicating that ISON continues to lag behind the more optimistic brightness predictions.

Curiosity sees unearthly moondance in Martian skies


Mars’ moon Deimos is occulted by Phobos on Aug. 1 as seen by Curiosity

What fun to live on a planet with TWO moons. Imagine stepping out into the Martian night to watch the moons Phobos and Deimos chase each other across the sky. NASA’s Curiosity rover did just that on Aug. 1 when mission control pointed its mast camera at the pair of tiny moons and snapped 41 photos as the larger and closer Phobos passed directly in front of little Deimos. In real time the “eclipse” took 55 seconds; the movie compresses that to 11. Even on Mars it was a marvelous night for a moondance.

With only one moon here on Earth, we miss out on the pleasures of dual moon gazing. The only thing that might come close is watching a cargo ship like the recent HTV-4 catch up and dock with the International Space Station.

Phobos orbits closer to Mars than Deimos and therefore completes a revolution around the planet more quickly, regularly overtaking its brother. The photos are the very first ever taken from Mars of an eclipse of one moon by the other.

Comparison showing how big the moons of Mars appear to be, as seen from its surface, in relation to the size that our moon appears to be seen from the Earth’s surface. Credit: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ.

A 100mm telephoto lens was used to make the images which clearly show some of the larger craters on Phobos.

Both moons are tiny compared to our own. Deimos’ diameter is 7.5 miles (12 km) and Phobos 14 miles (22 km). It takes me longer to drive to work than cross the length of Deimos.

Even though Phobos is only about twice the size of Deimos, it appears much larger from the surface because it orbits much closer to the Red Planet – 3,700 miles (6,000 km) vs.12,400 miles (20,000 km).

Orbiting above the Martian equator and so close to the surface, Phobos can’t be seen from Mars’ polar regions. Its great speed also means it overtakes the planet’s rotation rate, rising in the west and setting in the east during the Martian night. Here on Earth, the moon moves in the same west to east direction but much more slowly, so that the faster-rotating Earth shuttles it from east to west during the night.

Phobos and Deimos up close as photographed by spacecraft. NASA scientists are studying the recent Curiosity images to determine precise orbits for the two moons as well as to gain a better understanding of the interior of Mars. Credit: NASA

Phobos’ tight orbit will ultimately lead to its demise. Its gravity induces tidal bulges in the crust of Mars which lag behind the fast-orbiting moon, causing it to gradually slow down and drop closer to the planet’s surface. In 50-100 million years Phobos will spiral in close enough for Mars’ gravity to break it to pieces. Deimos alone will remain to dimly light the Martian night.

Nova Delphini 2013 brightens, now ranks among Top 35 brightest in history

A one-minute time exposure of the constellation Delphinus and the nova taken last night. I’ve labeled stars with magnitudes so you can track changes in the nova’s brightness. The magnitudes are visual ones taken from the Tycho catalog. Credit: Bob King

If it wasn’t for the bright moon, you’d be able to see the new nova with the naked eye even from the suburbs. But who knows? By tonight it could bust that barrier.

Last night Nova Delphini was magnitude 4.8 and still brightening. Richard Keen of Colorado saw it shortly before 2 a.m. this morning at 4.4. Already it’s some 10 times brighter than only two days ago at the time of its discovery. That puts it in the top 35 in recorded history!

I took a photo of Delphinus and the nova last night and annotated it with additional star magnitudes so you can watch it fluctuate in brightness in the coming nights. The smaller the number, the brighter the star.

Star atlases, like this view of Orion from Cambridge Atlas 2000.0, show star brightness as different sized dots. The smaller the dot, the fainter the star. Credit: Bob King

Astronomers use the magnitude scale to measure star and planet brightness. Each magnitude is 2.5 times brighter than the one below it. Deneb in the Northern Cross, which shines at 1st magnitude, is 2.5 times brighter than a 2nd magnitude star like the North Star, which in turn is 2.5 times brighter than a 3rd magnitude star and so on. A first magnitude star is 2.5 x 2.5 x 2.5 x 2.5 x 2.5 (about 100) times brighter than a 6th magnitude star, the typical naked eye limit under dark skies.

The larger the magnitude, the fainter the star. If something is very bright, its magnitude is a negative number. Vega shines at 0 mag. while Sirius, the brightest star, sparkles at -1.4 mag. Venus is brighter yet at -4.4. Click HERE for more information about star magnitudes.

Chart to help you find Nova Delphini 2013 with magnitudes shown. Stellarium

Keep an eye on the nova’s color. Right now it’s still in its explosive fireball phase and appears yellow through a telescope. That could change over the coming weeks as it either brightens or fades. Some novae turn a lovely pink. No matter what’s in store, you’ve got a front row seat as long as you have a good pair of binoculars and star chart. Go for it!

If you want the latest estimates of Nova Delphini’s brightness, go to aavso.org and type in N Del 2013 in the Star finder box, then click “Check reecent observations”.

Nova Delphini 2013 – a white dwarf with a yearn to burn

The bright nova in Delphinus photographed last night in a 16-inch telescope. Credit: John Chumack

It’s official. The new nova has been christened Nova Delphini 2013. Even better, it’s brightened since discovery. Last night a group of stargazers and I saw the pale yellow star with ease through the telescope. Later, when the moon had set, I was even able to spot the nova faintly with the naked eye at magnitude 5.8.

It’s been years since we’ve had an exploding star of this variety reach naked eye brightness. About 6-10 novae are discovered each year, most of them needing at least a small telescope to see. This year novae have popped off in Cepheus, Scorpius and possibly one in Aquila. Amateur astronomers are the nova finders, training cameras on swaths of the Milky Way night after night hoping to catch one in outburst.

The brightest nova ever recorded blew its top in Aquila the Eagle in 1918. V603 Aquilae shot all the up to -1.4 magnitude or nearly as bright as Sirius, the brightest star. You can still see it today in a 6-inch or larger telescope biding its time around magnitude 12 patiently waiting for another chance at nova-hood. Click HERE to get a finder chart.

The Milky Way is the favorite hunting ground for nova hunters. The dense concentration of stars along its band offers the best chance of finding the occasional nova. The galaxy averages about three dozen novae a year of which about a half dozen are discovered. Credit: Bob King

The Milky Way is the most lucrative hunting ground for novae hunting because stars are greatly concentrated along its length; that’s what creates the familiar hazy ribbon of light. You’re much more likely to spot one pointing your camera at millions of stars than at sparsely-strewn star fields outside the Milky Way band. Favorite hunting grounds include the Milky Way-streaked constellations of Scorpius, Sagittarius and Cygnus. I’ve never heard of one being found in the Big Dipper which is located well away from the galactic plane.

Novae occur in close binary systems where one star is a tiny but extremely compact white dwarf star. The dwarf pulls material into a disk around itself, some of which is funneled to the surface and ignites in a nova explosion. Credit: NASA

Just as there’s more than one type of tea, there are different kinds of novae. All involve close binary stars with a compact white dwarf stealing gas from its companion. The gas ultimately funnels down to the surface of the dwarf where it’s compacted by gravity and heated to high temperature on the star’s surface until it ignites in an explosive fireball. This is what you see when you look at a nova – a gigantic bomb going off.

Just to be clear, a nova doesn’t involve the destruction of the star, only a “shock to the system”. A supernova is a different beast entirely, resulting in the complete annihilation of a white dwarf or supergiant star. If a white dwarf accumulates too much matter from a companion and crosses the Chandrasekhar Limit, it can sidestep the nova stage and go straight to supernova.

Looking more closely we discover that novae come in two basic types – fast and slow. Fast ones rise abruptly to maximum brightness, some of them vaulting 10 magnitudes a day. Their decline can be equally swift.

All-sky Milky Way mosaic photo compiled by the 2MASS survey in dust-penetrating infrared light shows the flat disk, home to younger stars and fast novae and the fat central bulge, where more slow novae and older stars are found. Click to full-size version. Credit: 2MASS, J. Carpenter, T.H. Jarrett and R. Hurt.

Slow novae behave as you might expect, sometimes taking several months to reach peak brightness and often lingering for months. Fast novae, which arise from more massive white dwarfs, are concentrated in our galaxy’s flat disk; slow ones from smaller dwarfs are found in the central bulge. I suspect this recent nova is the fast variety.

Nova Delphini is still in the fireball stage engulfed by incandescent hydrogen gas. Astronomers have spectroscopically measured the speed of the ejecta from the blast at 1,250 miles (2,000 km) per secondThat’s 4.5 million miles per hour. Think about that for a second. Now picture the scene in your mind’s eye when you see the nova for yourself.

This map shows Delphinus and Sagitta, both of which are near the bright star Altair at the bottom of the Summer Triangle. You can star hop from the top of Delphinus to the star 29 Vulpeculae and from there to the nova. Or you can point your binoculars midway between Eta Sagittae and 29 Vul. Numbers in gold are star magnitudes. Stellarium

I’ve included a fresh map above. The numbers in gold are star magnitudes to help you track the nova’s brightness as it brightens or fades in the coming nights. The larger the number, the fainter the star. Click HERE for a nice explanation of star magnitudes. For more maps, please see my earlier Universe Today post.

Update 8/16: Last night Aug. 15 I saw the nova at magnitude 4.8 and it was even brighter this morning. That means it’s nearly ten times brighter than at discovery a two days ago.