It’s Time to See Vesta, the Brightest Asteroid

It’s Time to See Vesta, the Brightest Asteroid

It’s Time to See Vesta, the Brightest Asteroid 1600 900 Asteroid Day Asteroid Day

Vesta’s trajectory through the constellation Leo (The Lion) in March. Star Theta Leonis (Chertan) will help locate this asteroid. Credit:

Your best chance to observe an asteroid has arrived. On 29 March 1807, Vesta became the fourth asteroid to be discovered and this March, it will reach its closest distance to us and its greatest brightness for the year. It will be visible in the sky throughout the night and binoculars will be enough to see it. If you are in a very dark sky, it may even be possible to see the asteroid with the naked eye.

It will be easy to locate Vesta as it will wander through the constellation Leo, The Lion, from March to June. This constellation is easy to identify in the sky and the asteroid will appear close to some of its main stars during the period of its greatest brightness.

It will be an ideal time for you to do an Asteroid Day warm-up event, since this year marks the 10th anniversary of NASA’s Dawn probe’s arrival at Vesta. So why not organize a sequence of live activities about this asteroid? On clear nights, you will be able to show Vesta to your audience while explaining curious facts that the mission discovered, using images that Dawn beamed back to Earth. This will keep your audience attentive and serve as an alternative in case of bad weather.

Here are a list of ideas to host a full week of events: 

Portrait of the german astronomer Heinrich Wilhelm Matthias Olbers. Lithography by Rudolf Suhrlandt

On day one, present the asteroid’s history explaining the circumstances of its discovery. Vesta was considered a planet for some years until several similar objects were discovered. Make a short biography of its discoverer, the German Heinrich Wilhelm Olbers, citing some curiosities about his career and great contributions to astronomy. Did you know that he was the first person to discover two asteroids? Have you heard of the Olbers Paradox?

Use day two to explain what the criteria were for naming asteroids in the early 19th century and the differences for the nomenclature used today. Describe the character who inspired the name and some episodes involving Vesta in Roman mythology. Perhaps quote the first measurements made of the asteroid according to observations made between the end of the 19th century and the beginning of the 20th century.

You can use day three to talk about Vesta’s location in the Main Belt, mentioning the nearest neighboring asteroids. Explain the concept of synodic period, which is based on our movement around the Sun, and thus explain why Vesta’s oppositions do not occur annually for an Earth observer. Also describe Vesta’s rotation and compare it with other asteroids using a ranking from the fastest to the slowest. Finally, explain the various orbital inclinations that asteroids can have. Check that Vesta’s orbit has an inclination similar to planets or other smaller bodies. This interactive orbital diagram will assist you in presenting Vesta’s movements.

Orbits of Vesta and the inner planets of the Solar System. In March Vesta, Earth and the Sun will make a straight line with Earth in the middle, this is called opposition. Credit: JPL / NASA

Day four is for you to explain Vesta’s physical characteristics. Explain its characteristics (this page will help you) and encourage your audience to conclude why it was not classified as a dwarf planet. Compare the Vesta’s size with other asteroids (this amazing video will help you, too) and present the asteroids types and families, subdivisions based on the composition, mass and density of these celestial bodies.

Day five can be used to describe the exploration missions to Vesta. It was one target for the historic Dawn mission ten years ago, but other missions to Vesta have been proposed and canceled in the past such as ESA’s Asteroidal Gravity Optical and Radar Analysis (AGORA);  ESA and NASA’s Multiple Asteroid Orbiter with Solar Electric Propulsion (MAOSEP); and the Vesta spacecraft from the Soviet space programme. All of these missions were proposed between the 80s and 90s.

Day six is all about Vesta being the only asteroid known to have light and dark patches on the surface, similar to the Moon. Using this collection with detailed images of Vesta from the Dawn mission, you will be able to investigate Vesta’s geology and topography, exploring the main asteroid surface formations. You can also explain why Vesta is considered a protoplanet, a definition restricted to some objects in the Solar System. Conclude the presentation by mentioning that some bodies of the Solar System are thought to be fragments of Vesta caused by ancient impacts, and that there are also meteorites whose origin may be from this asteroid.

Geological map of Vesta showing craters and other formations. Credit: JPL / NASA

Finally, on day seven, go through the science fiction works that used asteroid Vesta as a destination. For example, the famous author Isaac Asimov described adventures on this asteroid in his works “Marooned Off Vesta” (1939) and “Lucky Starr and the Rings of Saturn” (1958). It will be very interesting to compare the asteroid Vesta imagined by Science fiction authors with the reality.

You can adjust the dates according to your availability, but remember that after March Vesta will gradually decrease its brightness.

Whatever you do, organize your series and be sure to register your activity on the Asteroid Day page. Have a good event!


Saulo Machado is the Asteroid Day Global Event Coordinator. Since 2016, Saulo has been the Brazil Regional Coordinator, where he helped organizers host their Asteroid Day events all over Brazil.

With a passion for astronomy and scientific dissemination, Saulo works as a business administrator in Fortaleza, Brazil. He is the Founder of the Astronomical Events Support Group (GaeA) and hosts Asteroid Day events in observatories, planetariums and astronomy groups throughout Brazil.