The July 2024 new moon occurs today when the Earth reaches its farthest point from the sun, known as aphelion.
The new moon arrives on July 5 at 6:57 p.m. Eastern Time (2257 UTC), according to the US Naval Observatory, and two days later the new moon will pass close to Mercury in the evening sky.
Earth reached aphelion today, which means the earth was further from the sun than at any other time in its annual orbit. Earth’s orbit around the sun is slightly elliptical, or oval-shaped, which means our distance from our star can vary by up to 3% throughout the year. This small difference is not significant enough to be noticeable to most observers.
New moons occur when the moon is directly between the sun and Earth; in many lunar calendar systems they mark the beginning of the lunar month. Technically, the sun and moon are in conjunction, on the same north-south line that passes through the celestial pole. The timing of the lunar phases is measured by where the moon is relative to the Earth, so a given phase occurs at the same time all over the world. Any variation is only due to the time zone it’s in – in Melbourne, Australia, for example, the new moon occurs at 8:57 a.m. on July 6.
New moons are invisible unless there is an eclipse; eclipses do not occur every new moon because the orbits of the moon and the Earth are not perfectly aligned; they are tilted relative to each other by about 5 degrees. The moon’s shadow then “misses” Earth most of the time. (The next solar eclipse is not until October 2, 2024).
Close transit with Mercury
In the evening hours of July 7, the moon will pass by Mercury as it exits the new phase; thin crescent will be some 3 degrees north on Wednesday at 2:33 PM ET, according to skywatching site In-the-Sky.org. At sunset, when the moon becomes visible, it will be about 16 degrees above the horizon; Mercury will be under the moon. But the planet won’t be really visible until 9:00 PM (sunset on that day is at around 8:29 p.m. in New York; times are similar in cities such as Chicago or Sacramento) and by then it will only be 8 degrees high, so from anywhere in the mid-northern latitudes the link will be a challenge to see – it will a flat, unobstructed and clear horizon is needed.
Observing the conjunction becomes easier as one approaches the equator. From lower latitudes (either north or south) the ecliptic, or the plane of Earth’s orbit projected onto the sky, makes a steeper angle with the horizon. This means that the planets, which all move within a few degrees of the ecliptic, tend to reach higher altitudes. (This is also why tropical sunsets appear so short, while sunsets at higher northern and southern latitudes appear longer—in the tropics the Sun is approaching the horizon almost straight down, while in more northern or southern regions it with a gentler slope).
From Miami the conjunction takes place at 14:33 local time, but both the moon and Mercury will be higher in the sky; THE the sun sets at 20:16 local time and at that point the moon is 20 degrees high and Mercury is 18 degrees above the western horizon. Around 8:30 PM, Mercury should just become visible and will still be about 12 degrees high, so with a clear, unobstructed horizon, one should be able to catch it.
From Bridgetown, Barbados (and similar latitudes) the moon will appear to be to the right of Mercury and at sunset, at 19:29 local timeThe Moon is a full 18 degrees high in the west, by 7pm it is still 14 degrees above the horizon, as is Mercury, and both will be more visible than from the continental US.
In the Western Hemisphere the conjunction itself occurs in the afternoon, in daylight, but as one moves east, the moment of conjunction shifts to the evening. From Madrid, Spain, the observing challenges are similar to those in New York (both cities are at almost the same latitude), but the connection occurs at 8:33 PM local time.
In the southern hemisphere, observation is a little easier – the days are shorter as it is austral winter. In Sao Paolo, the sun sets at 17:22 local time, and while conjunction occurs at 15:33, still during the day, at sunset the moon will be 18 degrees high in the northwest, and Mercury will appear above and to the left of the moon. The mercury won’t become visible until around 6pm and will still be around 12.5 degrees high. In Cape Town, where the connection takes place at 20:33 local time – sunset is at 5:51 p.m and the moon and Mercury set at 19:34; about half an hour after sunset, the pair is about 13 degrees high in the northwest.
Visible planets
Venus will appear in the evening sky, but will still be mostly lost in the sunlight; while it appears a little higher in the sky at sunset, as one approaches the equator, it is not more than five or six degrees high as the sky begins to darken.
Saturn is the first planet to rise, at 11:40 p.m. on July 5 in New York City. In the constellation of Aquarius, which is a fainter star cluster than most, it will be quite distinct in its own region of the sky. As the sky begins to lighten around 4:30 to 5:00 a.m. (the morning of July 6) it will be about 41 degrees above the south-southeast horizon.
Mars will be visible in the early hours of the morning; as the year progresses, it rises later and the planet will eventually be lost in the light of the dawning sun. On the night of the new moon (July 5-6) in mid-northern latitudes, the planet will rise around 2 a.m. – it rises at 2:03 a.m. in New York City, and the time will be similar in cities such as Chicago. (1:56 a.m. CDT), Denver (2:10 p.m. MDT) and Sacramento (2:18 p.m. PDT). Mars will be in the constellation Aires and will be easy to spot since Aires consists of fainter stars.
Jupiter rises behind Mars at 3:07 a.m. EDT in New York. Jupiter is in Taurus, and is to the left of and above Aldebaran, the brightest star in that constellation. Aldebaran is noticeably more orange and twinkling, making it easy to spot the planet, which is yellow-white and emits a steady light.
This means that around 4:30 a.m. local time at mid-northern latitudes, the three naked-eye planets farther from the sun than Earth will make a sort of line across the sky from the eastern horizon to the right, starting with Jupiter and ending with Saturn.
In the southern hemisphere, for example in Melbourne, Australia, (where the new moon is on July 6) the three planets will also form a line, but this time up and to the left (as in facing north). Saturn will also be higher in the sky. In Melbourne (and other mid-southern latitudes) Saturn will rise at 10:22pm AEST on July 6; when the planet transits (crossing the north-south line in the sky) at 4:43 a.m. on July 7 it will be a full 58 degrees above the northern horizon. Mars rises at 3.22am AEST, and Jupiter at 4.47am, Jupiter’s position in the sky relative to Aldebaran will be reversed; Jupiter will appear below Aldebaran rather than above (it will still appear to the left).
Summer stars
For Northern Hemisphere sky watchers, around 10 p.m., the Summer Triangle is high in the eastern sky; the “high” star is Vega, the brightest star in Lyra the Lyre, and is almost at the zenith (about 70 degrees above the horizon). The other two stars in the Summer triangle are Deneb and Altair, both of which are east (to the left) of Vega; from a place with a dark sky the Milky Way can be seen inside the Triangle. The three stars form an approximate right triangle with Altair at the southern end.
Turning left – heading north you will see the Big Dipper to the left (west) and just below Polaris, the pole star. Following the “pointers” (the two stars at the front of the Dipper’s bowl, Dubhe and Merak) to Polaris and continuing straight ahead, you encounter Cepheus, the king, and just below Cepheus is the “W” shape of Cassiopeia, which will be low in the northeast.
In the other direction, follow the handle of the great stick and “bow to Arcturus” the brightest star in Boötes, the shepherd, and continuing down you strike Spica, the brightest star in Virgo. Turning south (to the left), one sees the bright red star Antares, the heart of Scorpius, and in the darker parts of the sky looking up (north) from Scorpius, one sees Ophiuchus the healer, with Sagittarius and the shape of his “teapot” on the left. of Scorpio.
In the southern mid-latitudes, you can see the winter stars – darkness comes earlier. By 19:00 the sky is dark and the Southern Cross is high above the southern horizon, about 65 degrees. To the left of the Cross (east) is Alpha Centauri, also called Rigil Kentaurus, our nearest stellar neighbor. Further east and closer to the horizon is Scorpio, though upside down (from the perspective of a northern hemisphere observer) and very high in the sky; Antares is a full 47 degrees high by 7pm
To the southwest, the ship’s keel, Puppis, is being positioned and marked by Canopus, about 20 degrees above the southwest horizon. Canopus is the second brightest star in the night sky after Sirius. In the same region of the sky to the left (toward the south) are the Large Magellanic Clouds and the Small Magellanic Clouds, two satellite galaxies of the Milky Way.