Explanation: Even though you may have just read an email claiming Mars will be incredibly bright tonight, the brightest star on the horizon is not Mars. From central Iran on August 24th, the brightest star in this twilight desert skyview is Venus, aka the Evening Star. But a bright Mars is in the picture, just above and right of more brilliant Venus. Despite claims in the internet's annually returning Mars Hoax that Mars will be as big and bright as the Full Moon, this celestial scenario is very similar to the western sky you can see tonight. Along with Mars, the still beautiful vista includes Spica, alpha star of the constellation Virgo, above and left of Venus. Farther right of Venus, Saturn peeks through the sunset's fading glow just above the clouds. Near the opposite horizon, the Full Moon illuminating the desert is about 400,000 times brighter than Mars.
It's interesting that Venus looks much redder than Mars does here. That's because the light of Venus has been reddened by passing through the bank of mist seen in this picture, while Mars, on the other hand, is shining through much thinner mist and is much more unreddened by it.
I remember showing an incredibly reddened Venus to my mother many years ago. At first she refused to believe that this "yellow traffic light" was Venus. She insisted that it had to be some kind of bright orange street lamp seen in the distance!
Last edited by Ann on Fri Aug 27, 2010 6:18 am, edited 2 times in total.
Note, by the way, that it is Antares that is the rival of Mars (when it comes to displaying reddish color, of course.) It is not Betelgeause which is the rival of Mars. I agree! Antares looks redder than Betelgeuse! (Of course, I may be somewhat biased here, because the first time I saw Antares I was up at night sweeping the skies aimlessly with my binoculars, and there it was in the misty parts of the southern sky, an incredibly reddish point of light! It looked amazing! Betelgeuse, go and pull something old over you. (That is a word for word translation of a Swedish expression which means, you are not as good as you think you are, buddy, in fact... why don't you go and pull something old over you?)
Go and pull something old over you, Betelgeuse!
Last edited by Ann on Fri Aug 27, 2010 2:43 pm, edited 2 times in total.
I like Betelgeuse, too, and well remember how shocked I was to learn how big a star it is! As several APODs have put it: "If placed at the center of our Solar System, it would extend past the orbit of Jupiter."
Note, by the way, that it is Antares that is the rival of Mars (when it comes to displaying reddish color, of course.)
Antares is not just "the other Mars" because of its color, however.
It also lies close to the ecliptic, and therefore can appear close in the sky to Mars, making it easy to confuse the two.
Apparent magnitude Antares: +1.09
Apparent magnitude Mars: +1.84 to −2.91
<<The Moon's orbit is inclined to the ecliptic, and any stars with an ecliptic latitude of less than about 6.5 degrees may be occulted by it. There are three first magnitude stars that are sufficiently close to the ecliptic that they may be occulted by the Moon and by planets -- Regulus, Spica and Antares. Occultations of Aldebaran are presently only possible by the Moon, because the planets pass Aldebaran to the north. Neither planetary nor lunar occultations of Pollux are currently possible. However, in the far future, occultations of Aldebaran and Pollux will be possible, as they were in the far past. Some deep-sky objects, such as the Pleiades, can also be occulted by the moon.>>
<<The size of Antares may be calculated using its parallax and angular diameter. The angular diameter is known from lunar occultation measurements (41.3 ± 0.1 mas). This leads to a radius of 822 ± 80 solar radii.
Antares has a hot blue companion star, Antares B, of spectral type B2.5 at a separation of about 550 AUs. At magnitude 5.5, it is only 1/370th as bright visually as Antares A, although it shines with 170 times the Sun's luminosity. The companion is often described as green, but this is probably a contrast effect. Antares B can be observed with a small telescope for a few seconds during lunar occultations while Antares itself is hidden by the Moon; it was discovered by Johann Tobias Bürg during one such occultation on April 13, 1819. The orbit is poorly known, with an estimated period of 878 years.
* Cor Scorpii ("the Heart of Scorpion")
* Many of the old Egyptian temples are oriented so that the light of Antares plays a role in the ceremonies performed there.
* Antares was known as Satevis, one of the four "royal stars" of the Persians around 3000 BC.>>
With my usual sense of frustration, I struggle to find and identify the various stars/planets as listed in the APOD description.
BUT - what really fascinates me about this photo are the patterns in the desert sands!! Just by looking at the sand ripples, I wondered which direction the wind was blowing (( comparing many observations of ripples in the sand along the beach where I used to live )). However, noticing the bent directions of the few grasses about, it is truly mystifying that the ripples in the desert sands could form as they did .....
biddie67 wrote:With my usual sense of frustration, I struggle to find and identify the various stars/planets as listed in the APOD description.
The stretched parallelogram includes Venus & Mars on the short diagonal and Spica(left) and Saturn(right just above the clouds) along the long diagonal. Antares is the bright star way off on the left. The view is towards the Southwest.
biddie67 wrote:BUT - what really fascinates me about this photo are the patterns in the desert sands!! Just by looking at the sand ripples, I wondered which direction the wind was blowing (( comparing many observations of ripples in the sand along the beach where I used to live )). However, noticing the bent directions of the few grasses about, it is truly mystifying that the ripples in the desert sands could form as they did .....
Both the grasses and the ripples indicate that the wind is from the East.
Click to play embedded YouTube video.
<<Current ripple marks, unidirectional ripples, or asymmetrical ripple marks are asymmetrical in profile, with a gentle up-current slope and a steeper down-current slope. The down-current slope is the angle of repose, which depends on the shape of the sediment. These commonly form in fluvial and aeolian depositional environments, and are a signifier of the lower part of the Lower Flow Regime.>>
Ann wrote:It's interesting that Venus looks much redder than Mars does here. That's because the light of Venus has been reddened by passing through the bank of mist seen in this picture, while Mars, on the other hand, is shining through much thinner mist and is much more unreddened by it.
That may be part of the story. But also important is the nature of the instrument that recorded the image. A DSLR and good quality camera lens can place the light of a star on too few pixels to accurately reconstruct the color. The only astronomical object in this image that covers enough pixels to allow a reasonable color representation is Venus- which is likely reddened by the large airmass and possibly dust and aerosols. But Mars and Antares should both appear more red than they do. The reason they don't is probably a combination of things that have nothing to do with atmospheric conditions: they don't cover enough pixels, they appear to be saturated (note that Venus is saturated, and is actually white; it appears reddish because of the unsaturated halo around it), and JPEG compression doesn't handle tiny pixel groups very well- the artifacts around stars are obvious.
<<The Ares V (formerly known as the Cargo Launch Vehicle or CaLV) is the planned cargo launch component of the Constellation program, which would replace the Space Shuttle after its retirement in 2011. Ares V and the smaller Ares I are named after Ares, the Greek god of war, which is the equivalent to the Roman god Mars. Initially, the Ares V would launch the Earth Departure Stage and Altair lunar lander when NASA returns to the Moon, which is currently planned for 2019, but would also serve as the principal launcher for missions beyond the Earth-Moon system, including the program's ultimate goal, a manned mission to Mars after 2030. The unmanned Ares V would complement the smaller, and human-rated Ares I rocket for the launching of the 4-6 person Orion spacecraft. Both rockets, deemed safer than the current Space Shuttle, would utilize technologies developed for Project Apollo, the Shuttle, and the Delta IV EELV programs. On February 1, 2010, President Barack Obama announced a proposal to cancel the Constellation program effective with the U.S. 2011 fiscal year budget, subject to congressional approval.>>
<<The Sun-god Helios once spied Ares(Mars) and Aphrodite(Venus) enjoying each other secretly in the hall of Hephaestus, and he promptly reported the incident. Hephaestus contrived to catch the couple in the act, and so he fashioned a finely-knitted and nearly invisible net with which to snare the illicit lovers. At the appropriate time, this net was sprung, and trapped Ares and Aphrodite locked in very private embrace. But Hephaestus was not yet satisfied with his revenge — he invited the Olympian gods and goddesses to view the unfortunate pair. For the sake of modesty, the goddesses demurred, but the male gods went to witness the sight. Some commented on the beauty of Aphrodite, others remarked that they would eagerly trade places with Ares, but all who were present mocked the two. In a much later interpolated detail, Ares put the youth Alectryon by his door to warn them of Helios' arrival, as Helios would tell Hephaestus of Aphrodite's infidelity if the two were discovered, but Alectryon fell asleep. Helios discovered the two and alerted Hephaestus. Ares was furious and turned Alectryon into a rooster, which now never forgets to announce the arrival of the sun in the morning.
Ares's sacred birds were the woodpecker, the eagle owl and, especially in the south, the vulture. The birds of Ares (Ornithes Areioi) were a flock of feather-dart-dropping birds that guarded the Amazons' shrine of the god on a coastal island in the Black Sea.
Ares was rarely included in cult in ancient Greece, save at Sparta, where youths each sacrificed a puppy to Enyalios before engaging in the all-out ritual fighting. Just east of Sparta there was an archaic statue of the god in chains, to show that the spirit of war and victory was never to leave the city.The temple to Ares in the agora of Athens that Pausanias saw in the second century AD had only been moved and rededicated there during the time of Augustus; in essence it was a Roman temple to Mars. The Areopagus, the "mount of Ares" where Paul of Tarsus preached, is sited at some distance from the Acropolis; from archaic times it was a site of trials.>>
Venus is also bigger than Mars, so if Mars and Venus were the same distance from the Earth, Venus would still be brighter. The closest Venus gets to Earth in orbit is about 23 million miles and Mars about 50 million miles.
mpharo wrote:Venus is also bigger than Mars, so if Mars and Venus were the same distance from the Earth, Venus would still be brighter. The closest Venus gets to Earth in orbit is about 23 million miles and Mars about 50 million miles.
You also have to factor in that Venus is closer to the Sun, and it has a much higher albedo. Venus receives about 4.5x more light than Mars, and it also reflects about 4.5 times more light than Mars.